Search

In past winter seasons beginning in 1989, cloud seeding has been conducted in portions of northern Utah. This includes the northern Wasatch Range of eastern Box Elder and Cache Counties above approximately 6,000 feet MSL, and separate ranges in northwestern Box Elder County above the same elevation. The Northern Utah Seeding Program utilizes over 30 ground-based, manually-operated Cloud Nuclei Generator (CNG) sites, containing a 2% silver iodide solution. The goal of the seeding program is to augment wintertime snowpack/precipitation over the seeded watersheds. Cost sharing for the seeding program is provided by the Utah Division of Water Resources. Precipitation and snowfall were below normal again during the 2021-2022 winter season. A total of 1,469.75 CNG hours were conducted during 12 storm periods for the core program this season. There were no seeding suspensions during the 2021-2022 season.

The Duchesne County Water Conservancy District and the Uintah Water Conservancy District were joined by the Central Utah Water Conservancy District in supporting an operational seeding project, beginning in the 2002-2003 winter season. The intended target area of this program has been the southern slope of the Uinta Mountains above 8,000 feet. The High Uintas program currently utilizes 20 ground-based, manually operated Cloud Nuclei Generator (CNG) sites, burning a 2% Silver Iodide solution. Some sites established for the adjacent Western Uintas seeding program are also utilized to target the High Uintas. In addition, a remotely operated site located at Moon Lake has been added to the program. The goal of the seeding program is to augment wintertime snowpack/precipitation over the seeded watersheds. Cost sharing for the seeding program is provided by the Utah Division of Water Resources, with additional funds from the Lower Colorado River Basin States providing for an early-season extension to the seeding program. Precipitation and snowfall were well above average during the 2022-2023 winter season. The Uintas region fared very well this season compared to many surrounding areas. As of April 1, 2023, SNOTEL observations for the Natural Resource Conservation Service showed snow water content averaging about 187% of normal (median) for the Duchesne Basin and about 163% of normal for sites in the portions of the Uinta Range that compose the Green River Basin. Water year precipitation percentages were 159% of the median for the Duchesne Basin and around 133% of normal for sites in the Green River Basin. The snowpack percentages remained much higher than precipitation percentages this season due to early season precipitation in October and November essentially falling as all snow.

North American Weather Consultants (NAWC) has been involved in cloud seeding operations since the 1950s, beginning in California and in more recent decades, various other states and countries. Due to high natural precipitation variability and the increased demand for water, cloud seeding has been conducted over large areas of Utah for over 40 years. Cloud seeding in Utah is regulated and cost shared by the Utah Department of Natural Resources through the Division of Water Resources. Most cloud seeding programs in Utah are conducted for relatively high-yield areas of the Wasatch Range and Plateau, areas from the northern to southern borders of the state, as well as the Uinta Range in northeastern Utah. These programs are normally conducted from November to April in order to target winter storms. In 2020, NAWC was contacted by Daniel Campbell from the Range Valley Ranch requesting information regarding the potential for cloud seeding operations over the Tavaputs Plateau with the intent of increasing snowfall. Upon further discussion, it was determined that there were multiple entities with a vested interest in augmenting the precipitation that occurs in portions of the Rocky Mountains around the Tavaputs Plateau. In order to determine the feasibility of a program in this area of Utah, NAWC performed preliminary research to estimate the potential increase in precipitation and runoff in the area. Due to the remote nature of this portion of the Rocky Mountains, snow gauges and stream flow gauges are limited, as are historic records. Fortunately, NAWC’s experience in other portions of the state, particularly those portions of the state with similar geographical and climatological patterns, assisted in the development of the estimates we present in this report.

In many past winter seasons, cloud seeding has been conducted in several different regions within central and southern Utah. Since the mid-1970s seeding has been concentrated in the mountainous watersheds from Millard and Sanpete Counties southward to the Pine Valley Mountains and Washington County and the headwaters of the Sevier River in Iron and Garfield Counties. The mountainous portions of Tooele and Juab Counties have been included as seeding target areas since 1988. The intended target areas of this program generally include terrain above 7,000 feet elevation. The Southern and Central Utah Seeding Program utilizes approximately 70 ground-based, manually-operated (Cloud Nuclei Generator, or CNG) sites, containing a 2% silver iodide solution. The goal of the seeding program is to augment wintertime snowpack/precipitation over the seeded watersheds. Cost sharing for the seeding program is provided by the Utah Division of Water Resources, and additional funds from the Lower Colorado River Basin States has resulted in early-season (November 1st-15th) and late season (March 16th - April 15th) extensions to the seeding program since 2010. Precipitation and snowfall were well above normal during the 2022-2023 winter season, with some locations approaching record totals for the winter season. A total of 3594.00 CNG hours were conducted during 21 storm periods for the core program this season. An additional 737.25 hours of seeding were conducted during three early-season storm periods and 908.00 hours of seeding were conducted during six late-season storm periods for the Lower Basin Extension periods. Beginning on March 16 and continuing for the remainder of the season, any seeding that would affect the Virgin River Headwaters (e.g., Pine Valley Mountains, Cedar Breaks area in N/NW flow) were suspended due to excessive snowpack in this area which prompted concerns regarding potential snowmelt flooding.

A total of 26 winter seasons of cloud seeding have been conducted in portions of the Western Uinta Range in Utah. The Western Uintas program utilizes 11 ground-based, manually operated (Cloud Nuclei Generator, or CNG) sites, containing a 2% silver iodide solution. The goal of the seeding program is to augment wintertime snowpack/precipitation over the seeded watersheds. The areas targeted for seeding have included the upper portions of both the Weber River and the Provo River drainages in most years. Precipitation and snowfall were well above normal during the 2022-2023 winter season, with snow water equivalent for the Weber-Ogden River Basin averaging about 198% of the median value on April 1st. The water year precipitation through April 1st averaged 159% of the normal median value across the basin. The Provo River basin had corresponding April 1st averages of 207% of median snowpack and 170% of median precipitation. A total of 1332 CNG hours were conducted during 22 storm periods this season, out of a maximum budgeted 1,500 hours. By late March, it became apparent that flooding risks outweighed further benefits of the seeding program this season. Although higher elevation SNOTEL sites that have been established by the Division of Water Resources for program suspension criteria in this area were still below their pre-defined suspension thresholds, it was observed that the lower elevation snowpack in each drainage basin were reaching unprecedented highs. Given this, and the continued unseasonably cold weather into the spring season, the seeding program was suspended and ended for the season a week early on March 24. Evaluations of the effectiveness of the cloud seeding program were made for both the 2022-2023 winter season as well as the past 2 seeded winter seasons combined. These evaluations utilize SNOTEL records collected by the Natural Resources Conservation Service (NRCS) at selected sites within and surrounding the seeded target area. Analyses of the effects

Salt Lake City Department of Public Works (SLCDPW) initially sponsored winter cloud seeding programs targeting the Six Creeks drainage basin in Water Years 1989 through 1996, with NAWC operating these programs. NAWC analysis of potential effects of the seeding indicated positive effects (~6% to 17% for water years 1989 and 1990, Thompson, et al., 1990). It was NAWC’s understanding that this program was discontinued following water year (1996) due to budgetary considerations. SLCDPW expressed an interest in the fall of 2018 in re-establishing a cloud seeding program to impact the Six Creeks drainage basins that provide runoff to the Salt Lake Valley. A proposal was drawn up by NAWC and accepted by SLCDPU in the fall of 2018, and the first season of operations for the current program began in December 2019. The current season’s cloud seeding program began on November 15, 2022 and was contracted through April 15, 2023. However, abnormally high snowpack this season (with some SNOTEL sites being above their entire recorded record) resulted in an early end to the seeding program, based on discussion of flooding potential between NAWC and the program sponsors including the Division of Water Resources. The program was suspended in February, with the last seeded event occurring on February 8. A total of 16 storm events were seeded during the 2022-2023 season, using a network of eight ground-based silver iodide generators, although a couple of the early season events were targeted primarily to the Snowbird resort program which is within the larger Six Creeks watershed. In total there were three seeded events in November, six in December, five in January, and two in February. A total of 839.25 cumulative hours of seeding generator operations were conducted specifically for the Six Creeks program during the season.

Declining water levels of Great Salt Lake threaten economic activity, local public health, and ecosystems. The situation requires urgent action. Fortunately, science provides crucial perspective, understanding, and scenarios for policymakers to chart a path forward. Many policy levers can help return the lake to healthy levels. Utah's research universities formed the Great Salt Lake Strike Team to provide a primary point of contact for policymakers as they address record-low elevations of Great Salt Lake. Together with state agency professionals, the Strike Team brings together experts in public policy, hydrology, water management, climatology, and dust to provide impartial, data-informed, and solution-oriented support for Utah decision-makers. The Strike Team does not advocate but rather functions in a scientific/ policy advisory role as a service to the state.

Salt Lake City Department of Public Works (SLCDPW) initially sponsored winter cloud seeding programs targeting the Six Creeks drainage basin in Water Years 1989 through 1996, with NAWC operating these programs. NAWC analysis of potential effects of the seeding indicated positive effects (~6% to 17% for water years 1989 and 1990, Thompson, et al., 1990). It was NAWC’s understanding that this program was discontinued following water year (1996) due to budgetary considerations. SLCDPW expressed an interest in the fall of 2018 in re-establishing a cloud seeding program to impact the Six Creeks drainage basins that provide runoff to the Salt Lake Valley. A proposal was drawn up by NAWC and accepted by SLCDPU in the fall of 2018, and the first season of operations for the current program began in December 2019. The current season’s cloud seeding program began on November 15, 2021 and ended on April 15, 2022. A total of 21 storm events were seeded during all or portions of 35 days during the 2021-2022 season, using a network of eight ground-based silver iodide generators. No seeded storm events occurred in November this season although there were seven seeded events in December, followed by two in January, two in February, seven in March and three additional seeded events in April. A total of 1060.75 cumulative hours of seeding generator operations were conducted during the season from the ground sites.

A total of 26 winter seasons of cloud seeding have been conducted in portions of the western Uinta Range in Utah. The Western Uintas program utilizes 11 ground-based, manually-operated (Cloud Nuclei Generator, or CNG) sites, containing a 2% silver iodide solution. The goal of the seeding program is to augment wintertime snowpack/precipitation over the seeded watersheds. The areas targeted for seeding have included the upper portions of both the Weber River and the Provo River drainages in most years. Precipitation and snowfall were below normal during the 2021-2022 winter season, with snow water equivalent for the Weber-Ogden River basin averaging about 66% of the median value on April 1st. The water year precipitation through April 1st averaged 90% of the normal median value across the basin. The Provo River basin had corresponding April 1st averages of 71% of median snowpack and 97% of median precipitation. A total of 1089.25 CNG hours were conducted during 17 storm periods this season, out of a maximum budgeted 2,500 hours. There was no seeding suspension during the 2021-2022.

In many past winter seasons, cloud seeding has been conducted in several different regions within central and southern Utah. Since the mid-1970s seeding has been concentrated in the mountainous watersheds from Millard and Sanpete Counties southward to the Pine Valley Mountains and Washington County and the headwaters of the Sevier River in Iron and Garfield Counties. The mountainous portions of Tooele and Juab Counties have been included as seeding target areas since 1988. The intended target areas of this program generally include terrain above 7,000 feet elevation. The Southern and Central Utah Seeding Program utilizes approximately 70 ground-based, manually-operated (Cloud Nuclei Generator, or CNG) sites, containing a 2% silver iodide solution. The goal of the seeding program is to augment wintertime snowpack/precipitation over the seeded watersheds. Cost sharing for the seeding program is provided by the Utah Division of Water Resources, and additional funds from the Lower Colorado River Basin States has resulted in early-season (November 1st-15th) and late season (March 16th - April 15th) extensions to the seeding program since 2010. Due to abnormally dry conditions this season and the past several years, the decision was made to extend the core seeding program through April 30th. Precipitation and snowfall were well below normal during the 2021-2022 winter season. A total of 2678.5 CNG hours were conducted during 14 storm periods for the core program this season. An additional 681.25 hours of seeding were conducted during five late-season storm periods for the early and late season Lower Basin Extension periods. An additional 591.25 hours of seeding were conducted for the special core program extension through late March and April during some of these same late-season events. There were no seeding suspensions during the 2021-2022 season.

Utah has been cloud seeding since the early 1950s to help augment the state's water supply. The Cloud Seeding Act of 1973 gave authority to the Utah Division of Water Resources to oversee state cloud seeding projects. Ground-based seeders shoot silver iodide into winter clouds where it helps form ice crystals. The seeders are placed along foothills and higher elevations where the release of the cloud seeds is timed so that air currents carry them high into the cloud. This process is effective because clouds are formed by water vapor and dust. Under certain natural conditions those water droplets will freeze together around the dust or other particles and, when heavy enough, will fall from the sky as snow. Often, there is more snow that can fall but limited by the number of particles around which ice crystals can form. That is why adding particles, or seeds, facilitates and accelerates the process which may lead to more snow falling than would have under natural conditions. Since snowpack is Utah's largest reservoir, increasing the amount of snow that falls is a win for the water supply.It doesn't work just anywhere. The conditions have to be right. Luckily, Utah's topography, climate and reservoirs make winter snowpack enhancement cost-effective. Statistical analysis shows an average increase in precipitation of 5-15% in seeded areas at a cost of about $2.18 per acre-foot for the additional water. The field program runs November to April and is funded jointly by the state and local water interests.Conditions must be suitable for cloud seeding. Cloud seeding can only occur when there is sufficient water in the atmosphere, which is why Utah's cloud seeding takes place only in the winter. (The summer months are often too dry and don't have enough clouds to seed.)The Division is authorized by the Utah Legislature to split costs with local sponsors up to a maximum of $350,000 per year. There is insufficient funding or local support for a summer seeding program and Utah's

Utah has been cloud seeding since the early 1950s to help augment the state's water supply. The Cloud Seeding Act of 1973 gave authority to the Utah Division of Water Resources to oversee state cloud seeding projects. Ground-based seeders shoot silver iodide into winter clouds where it helps form ice crystals. The seeders are placed along foothills and higher elevations where the release of the cloud seeds is timed so that air currents carry them high into the cloud. This process is effective because clouds are formed by water vapor and dust. Under certain natural conditions those water droplets will freeze together around the dust or other particles and, when heavy enough, will fall from the sky as snow. Often, there is more snow that can fall but limited by the number of particles around which ice crystals can form. That is why adding particles, or seeds, facilitates and accelerates the process which may lead to more snow falling than would have under natural conditions. Since snowpack is Utah's largest reservoir, increasing the amount of snow that falls is a win for the water supply. It doesn't work just anywhere. The conditions have to be right. Luckily, Utah's topography, climate and reservoirs make winter snowpack enhancement cost-effective. Statistical analysis shows an average increase in precipitation of 5-15% in seeded areas at a cost of about $2.18 per acre-foot for the additional water. The field program runs November to April and is funded jointly by the state and local water interests. Conditions must be suitable for cloud seeding. Cloud seeding can only occur when there is sufficient water in the atmosphere, which is why Utah's cloud seeding takes place only in the winter. (The summer months are often too dry and don't have enough clouds to seed.) The Division is authorized by the Utah Legislature to split costs with local sponsors up to a maximum of $350,000 per year. There is insufficient funding or local support for a summer seeding program and Uta

2022 marks the 75th anniversary of the Utah Board of Water Resources! It was originally named the Utah Water and Power Board in 1947. The Board administers revolving funds to develop new water projects and refurbish aging projects throughout the state of Utah. Seventy-five years, 1,530 projects, and $988M in Board Funding. From dam development and upgrades, to water data collection and planning, and hundreds of critical projects in between, the Board has worked hard to protect Utah's water. Now more than ever, they're committed to collaboration with the water community to address the challenges ahead of us.

A review of duties and funding programs of the Division and Board of Water Resources.

Utah has been cloud seeding since the early 1950s to help augment the state's water supply. The Cloud Seeding Act of 1973 gave authority to the Utah Division of Water Resources to oversee state cloud seeding projects. Ground-based seeders shoot silver iodide into winter clouds where it helps form ice crystals. The seeders are placed along foothills and higher elevations where the release of the cloud seeds is timed so that air currents carry them high into the cloud. This process is effective because clouds are formed by water vapor and dust. Under certain natural conditions those water droplets will freeze together around the dust or other particles and, when heavy enough, will fall from the sky as snow. Often, there is more snow that can fall but limited by the number of particles around which ice crystals can form. That is why adding particles, or seeds, facilitates and accelerates the process which may lead to more snow falling than would have under natural conditions. Since snowpack is Utah's largest reservoir, increasing the amount of snow that falls is a win for the water supply. It doesn't work just anywhere. The conditions have to be right. Luckily, Utah's topography, climate and reservoirs make winter snowpack enhancement cost-effective. Statistical analysis shows an average increase in precipitation of 5-15% in seeded areas at a cost of about $2.18 per acre-foot for the additional water. The field program runs November to April and is funded jointly by the state and local water interests. Conditions must be suitable for cloud seeding. Cloud seeding can only occur when there is sufficient water in the atmosphere, which is why Utah's cloud seeding takes place only in the winter. (The summer months are often too dry and don't have enough clouds to seed.) The Division is authorized by the Utah Legislature to split costs with local sponsors up to a maximum of $350,000 per year. There is insufficient funding or local support for a summer seeding program and Uta

Utah has been cloud seeding since the early 1950s to help augment the state's water supply. The Cloud Seeding Act of 1973 gave authority to the Utah Division of Water Resources to oversee state cloud seeding projects. Ground-based seeders shoot silver iodide into winter clouds where it helps form ice crystals. The seeders are placed along foothills and higher elevations where the release of the cloud seeds is timed so that air currents carry them high into the cloud. This process is effective because clouds are formed by water vapor and dust. Under certain natural conditions those water droplets will freeze together around the dust or other particles and, when heavy enough, will fall from the sky as snow. Often, there is more snow that can fall but limited by the number of particles around which ice crystals can form. That is why adding particles, or seeds, facilitates and accelerates the process which may lead to more snow falling than would have under natural conditions. Since snowpack is Utah's largest reservoir, increasing the amount of snow that falls is a win for the water supply. It doesn't work just anywhere. The conditions have to be right. Luckily, Utah's topography, climate and reservoirs make winter snowpack enhancement cost-effective. Statistical analysis shows an average increase in precipitation of 5-15% in seeded areas at a cost of about $2.18 per acre-foot for the additional water. The field program runs November to April and is funded jointly by the state and local water interests. Conditions must be suitable for cloud seeding. Cloud seeding can only occur when there is sufficient water in the atmosphere, which is why Utah's cloud seeding takes place only in the winter. (The summer months are often too dry and don't have enough clouds to seed.) The Division is authorized by the Utah Legislature to split costs with local sponsors up to a maximum of $350,000 per year. There is insufficient funding or local support for a summer seeding program and Uta

2022 marks the 75th anniversary of the Utah Board of Water Resources! It was originally named the Utah Water and Power Board in 1947. The Board administers revolving funds to develop new water projects and refurbish aging projects throughout the state of Utah. Seventy-five years, 1,530 projects, and $988M in Board Funding. From dam development and upgrades, to water data collection and planning, and hundreds of critical projects in between, the Board has worked hard to protect Utah's water. Now more than ever, they're committed to collaboration with the water community to address the challenges ahead of us.

A review of duties and funding programs of the Division and Board of Water Resources.

Utah has been cloud seeding since the early 1950s to help augment the state's water supply. The Cloud Seeding Act of 1973 gave authority to the Utah Division of Water Resources to oversee state cloud seeding projects. Ground-based seeders shoot silver iodide into winter clouds where it helps form ice crystals. The seeders are placed along foothills and higher elevations where the release of the cloud seeds is timed so that air currents carry them high into the cloud. This process is effective because clouds are formed by water vapor and dust. Under certain natural conditions those water droplets will freeze together around the dust or other particles and, when heavy enough, will fall from the sky as snow. Often, there is more snow that can fall but limited by the number of particles around which ice crystals can form. That is why adding particles, or seeds, facilitates and accelerates the process which may lead to more snow falling than would have under natural conditions. Since snowpack is Utah's largest reservoir, increasing the amount of snow that falls is a win for the water supply.It doesn't work just anywhere. The conditions have to be right. Luckily, Utah's topography, climate and reservoirs make winter snowpack enhancement cost-effective. Statistical analysis shows an average increase in precipitation of 5-15% in seeded areas at a cost of about $2.18 per acre-foot for the additional water. The field program runs November to April and is funded jointly by the state and local water interests.Conditions must be suitable for cloud seeding. Cloud seeding can only occur when there is sufficient water in the atmosphere, which is why Utah's cloud seeding takes place only in the winter. (The summer months are often too dry and don't have enough clouds to seed.)The Division is authorized by the Utah Legislature to split costs with local sponsors up to a maximum of $350,000 per year. There is insufficient funding or local support for a summer seeding program and Utah's

Utah has been cloud seeding since the early 1950s to help augment the state's water supply. The Cloud Seeding Act of 1973 gave authority to the Utah Division of Water Resources to oversee state cloud seeding projects. Ground-based seeders shoot silver iodide into winter clouds where it helps form ice crystals. The seeders are placed along foothills and higher elevations where the release of the cloud seeds is timed so that air currents carry them high into the cloud. This process is effective because clouds are formed by water vapor and dust. Under certain natural conditions those water droplets will freeze together around the dust or other particles and, when heavy enough, will fall from the sky as snow. Often, there is more snow that can fall but limited by the number of particles around which ice crystals can form. That is why adding particles, or seeds, facilitates and accelerates the process which may lead to more snow falling than would have under natural conditions. Since snowpack is Utah's largest reservoir, increasing the amount of snow that falls is a win for the water supply.It doesn't work just anywhere. The conditions have to be right. Luckily, Utah's topography, climate and reservoirs make winter snowpack enhancement cost-effective. Statistical analysis shows an average increase in precipitation of 5-15% in seeded areas at a cost of about $2.18 per acre-foot for the additional water. The field program runs November to April and is funded jointly by the state and local water interests.Conditions must be suitable for cloud seeding. Cloud seeding can only occur when there is sufficient water in the atmosphere, which is why Utah's cloud seeding takes place only in the winter. (The summer months are often too dry and don't have enough clouds to seed.)The Division is authorized by the Utah Legislature to split costs with local sponsors up to a maximum of $350,000 per year. There is insufficient funding or local support for a summer seeding program and Utah's

Utah has been cloud seeding since the early 1950s to help augment the state's water supply. The Cloud Seeding Act of 1973 gave authority to the Utah Division of Water Resources to oversee state cloud seeding projects. Ground-based seeders shoot silver iodide into winter clouds where it helps form ice crystals. The seeders are placed along foothills and higher elevations where the release of the cloud seeds is timed so that air currents carry them high into the cloud. This process is effective because clouds are formed by water vapor and dust. Under certain natural conditions those water droplets will freeze together around the dust or other particles and, when heavy enough, will fall from the sky as snow. Often, there is more snow that can fall but limited by the number of particles around which ice crystals can form. That is why adding particles, or seeds, facilitates and accelerates the process which may lead to more snow falling than would have under natural conditions. Since snowpack is Utah's largest reservoir, increasing the amount of snow that falls is a win for the water supply. It doesn't work just anywhere. The conditions have to be right. Luckily, Utah's topography, climate and reservoirs make winter snowpack enhancement cost-effective. Statistical analysis shows an average increase in precipitation of 5-15% in seeded areas at a cost of about $2.18 per acre-foot for the additional water. The field program runs November to April and is funded jointly by the state and local water interests. Conditions must be suitable for cloud seeding. Cloud seeding can only occur when there is sufficient water in the atmosphere, which is why Utah's cloud seeding takes place only in the winter. (The summer months are often too dry and don't have enough clouds to seed.) The Division is authorized by the Utah Legislature to split costs with local sponsors up to a maximum of $350,000 per year. There is insufficient funding or local support for a summer seeding program and Uta

Utah has been cloud seeding since the early 1950s to help augment the state's water supply. The Cloud Seeding Act of 1973 gave authority to the Utah Division of Water Resources to oversee state cloud seeding projects. Ground-based seeders shoot silver iodide into winter clouds where it helps form ice crystals. The seeders are placed along foothills and higher elevations where the release of the cloud seeds is timed so that air currents carry them high into the cloud. This process is effective because clouds are formed by water vapor and dust. Under certain natural conditions those water droplets will freeze together around the dust or other particles and, when heavy enough, will fall from the sky as snow. Often, there is more snow that can fall but limited by the number of particles around which ice crystals can form. That is why adding particles, or seeds, facilitates and accelerates the process which may lead to more snow falling than would have under natural conditions. Since snowpack is Utah's largest reservoir, increasing the amount of snow that falls is a win for the water supply.It doesn't work just anywhere. The conditions have to be right. Luckily, Utah's topography, climate and reservoirs make winter snowpack enhancement cost-effective. Statistical analysis shows an average increase in precipitation of 5-15% in seeded areas at a cost of about $2.18 per acre-foot for the additional water. The field program runs November to April and is funded jointly by the state and local water interests.Conditions must be suitable for cloud seeding. Cloud seeding can only occur when there is sufficient water in the atmosphere, which is why Utah's cloud seeding takes place only in the winter. (The summer months are often too dry and don't have enough clouds to seed.)The Division is authorized by the Utah Legislature to split costs with local sponsors up to a maximum of $350,000 per year. There is insufficient funding or local support for a summer seeding program and Utah's

In many past winter seasons, cloud seeding has been conducted in several different regions within central and southern Utah. Since the mid-1970s seeding has been concentrated in the mountainous watersheds from Millard and Sanpete Counties southward to the Pine Valley Mountains and Washington County and the headwaters of the Sevier River in Iron and Garfield Counties. The mountainous portions of Tooele and Juab Counties have been included as seeding target areas since 1988. The intended target areas of this program generally include terrain above 7,000 feet elevation. The Southern and Central Utah Seeding Program utilizes approximately 70 ground-based, manually-operated (Cloud Nuclei Generator, or CNG) sites, containing a 2% silver iodide solution. The goal of the seeding program is to augment wintertime snowpack/precipitation over the seeded watersheds. Cost sharing for the seeding program is provided by the Utah Division of Water Resources, and additional funds from the Lower Colorado River Basin States has resulted in early-season (November 1st-15th) and late season (March 16th– April 15th) extensions to the seeding program since 2010. Precipitation and snowfall were generally near normal during the 2019-2020 winter season, with the higher totals generally observed in far southern Utah. A total of 3,602.25 CNG hours were conducted during 18 storm periods for the core program this season, out of a maximum budgeted 6,500 hours. An additional 1,376.75 hours of seeding were conducted during 9 storm periods for the late-season Lower Basin Extension. There were no seeding suspensions during the 2019-2020 season.

A total of 25 winter seasons of cloud seeding have been conducted in portions of the western Uinta Range in Utah. The Western Uintas program utilizes 12 ground-based, manually-operated (Cloud Nuclei Generator, or CNG) sites, containing a 2% silver iodide solution. The areas targeted for seeding have included the upper portions of both the Weber River and the Provo River drainages in most years. Precipitation and snowfall were below normal during the 2020-2021 winter season, with snow water equivalent for the Weber-Ogden River basin averaging about 74% of the median value on April 1st. The water year precipitation through April 1st averaged 67% of the normal (mean value) across the basin. The Provo River basin had corresponding April 1st averages of 78% of median snowpack and 71% of mean precipitation. A total of 1272.75 CNG hours were conducted during 19 storm periods this season, out of a maximum budgeted 2,500 hours. There was one seeding suspension during the 2020-2021 season, on February 16th due to extreme avalanche danger. Evaluations of the effectiveness of the cloud seeding program were made for both the past winter season and for the 26 seeded winter seasons combined. These evaluations utilize SNOTEL records collected by the Natural Resources Conservation Service (NRCS) at selected sites within and surrounding the seeded target area. Analyses of the effects of seeding on target area precipitation and snow water content have been conducted for this seeding program, utilizing target/control comparison techniques. Multi-season target vs. control evaluations have been performed to compare seasonal performance of the target area in comparison to the control areas during both seeded and non-seeded years. These studies have evaluated the performance of two variables related to seasonal storm productivity, namely total seasonal precipitation and April 1 snowpack (measured in inches of liquid water equivalence). Due to the short period of measurement for total preci

Utah has been cloud seeding since the early 1950s to help augment the state's water supply. The Cloud Seeding Act of 1973 gave authority to the Utah Division of Water Resources to oversee state cloud seeding projects. Ground-based seeders shoot silver iodide into winter clouds where it helps form ice crystals. The seeders are placed along foothills and higher elevations where the release of the cloud seeds is timed so that air currents carry them high into the cloud. This process is effective because clouds are formed by water vapor and dust. Under certain natural conditions those water droplets will freeze together around the dust or other particles and, when heavy enough, will fall from the sky as snow. Often, there is more snow that can fall but limited by the number of particles around which ice crystals can form. That is why adding particles, or seeds, facilitates and accelerates the process which may lead to more snow falling than would have under natural conditions. Since snowpack is Utah's largest reservoir, increasing the amount of snow that falls is a win for the water supply. It doesn't work just anywhere. The conditions have to be right. Luckily, Utah's topography, climate and reservoirs make winter snowpack enhancement cost-effective. Statistical analysis shows an average increase in precipitation of 5-15% in seeded areas at a cost of about $2.18 per acre-foot for the additional water. The field program runs November to April and is funded jointly by the state and local water interests. Conditions must be suitable for cloud seeding. Cloud seeding can only occur when there is sufficient water in the atmosphere, which is why Utah's cloud seeding takes place only in the winter. (The summer months are often too dry and don't have enough clouds to seed.) The Division is authorized by the Utah Legislature to split costs with local sponsors up to a maximum of $350,000 per year. There is insufficient funding or local support for a summer seeding program and Uta

Utah has been cloud seeding since the early 1950s to help augment the state's water supply. The Cloud Seeding Act of 1973 gave authority to the Utah Division of Water Resources to oversee state cloud seeding projects. Ground-based seeders shoot silver iodide into winter clouds where it helps form ice crystals. The seeders are placed along foothills and higher elevations where the release of the cloud seeds is timed so that air currents carry them high into the cloud. This process is effective because clouds are formed by water vapor and dust. Under certain natural conditions those water droplets will freeze together around the dust or other particles and, when heavy enough, will fall from the sky as snow. Often, there is more snow that can fall but limited by the number of particles around which ice crystals can form. That is why adding particles, or seeds, facilitates and accelerates the process which may lead to more snow falling than would have under natural conditions. Since snowpack is Utah's largest reservoir, increasing the amount of snow that falls is a win for the water supply. It doesn't work just anywhere. The conditions have to be right. Luckily, Utah's topography, climate and reservoirs make winter snowpack enhancement cost-effective. Statistical analysis shows an average increase in precipitation of 5-15% in seeded areas at a cost of about $2.18 per acre-foot for the additional water. The field program runs November to April and is funded jointly by the state and local water interests. Conditions must be suitable for cloud seeding. Cloud seeding can only occur when there is sufficient water in the atmosphere, which is why Utah's cloud seeding takes place only in the winter. (The summer months are often too dry and don't have enough clouds to seed.) The Division is authorized by the Utah Legislature to split costs with local sponsors up to a maximum of $350,000 per year. There is insufficient funding or local support for a summer seeding program and Uta

Utah has been cloud seeding since the early 1950s to help augment the state's water supply. The Cloud Seeding Act of 1973 gave authority to the Utah Division of Water Resources to oversee state cloud seeding projects. Ground-based seeders shoot silver iodide into winter clouds where it helps form ice crystals. The seeders are placed along foothills and higher elevations where the release of the cloud seeds is timed so that air currents carry them high into the cloud. This process is effective because clouds are formed by water vapor and dust. Under certain natural conditions those water droplets will freeze together around the dust or other particles and, when heavy enough, will fall from the sky as snow. Often, there is more snow that can fall but limited by the number of particles around which ice crystals can form. That is why adding particles, or seeds, facilitates and accelerates the process which may lead to more snow falling than would have under natural conditions. Since snowpack is Utah's largest reservoir, increasing the amount of snow that falls is a win for the water supply. It doesn't work just anywhere. The conditions have to be right. Luckily, Utah's topography, climate and reservoirs make winter snowpack enhancement cost-effective. Statistical analysis shows an average increase in precipitation of 5-15% in seeded areas at a cost of about $2.18 per acre-foot for the additional water. The field program runs November to April and is funded jointly by the state and local water interests. Conditions must be suitable for cloud seeding. Cloud seeding can only occur when there is sufficient water in the atmosphere, which is why Utah's cloud seeding takes place only in the winter. (The summer months are often too dry and don't have enough clouds to seed.) The Division is authorized by the Utah Legislature to split costs with local sponsors up to a maximum of $350,000 per year. There is insufficient funding or local support for a summer seeding program and Uta

Utah has been cloud seeding since the early 1950s to help augment the state's water supply. The Cloud Seeding Act of 1973 gave authority to the Utah Division of Water Resources to oversee state cloud seeding projects. Ground-based seeders shoot silver iodide into winter clouds where it helps form ice crystals. The seeders are placed along foothills and higher elevations where the release of the cloud seeds is timed so that air currents carry them high into the cloud. This process is effective because clouds are formed by water vapor and dust. Under certain natural conditions those water droplets will freeze together around the dust or other particles and, when heavy enough, will fall from the sky as snow. Often, there is more snow that can fall but limited by the number of particles around which ice crystals can form. That is why adding particles, or seeds, facilitates and accelerates the process which may lead to more snow falling than would have under natural conditions. Since snowpack is Utah's largest reservoir, increasing the amount of snow that falls is a win for the water supply. It doesn't work just anywhere. The conditions have to be right. Luckily, Utah's topography, climate and reservoirs make winter snowpack enhancement cost-effective. Statistical analysis shows an average increase in precipitation of 5-15% in seeded areas at a cost of about $2.18 per acre-foot for the additional water. The field program runs November to April and is funded jointly by the state and local water interests. Conditions must be suitable for cloud seeding. Cloud seeding can only occur when there is sufficient water in the atmosphere, which is why Utah's cloud seeding takes place only in the winter. (The summer months are often too dry and don't have enough clouds to seed.) The Division is authorized by the Utah Legislature to split costs with local sponsors up to a maximum of $350,000 per year. There is insufficient funding or local support for a summer seeding program and Uta

In many past winter seasons, cloud seeding has been conducted in several different regions within central and southern Utah. Since the mid-1970s seeding has been concentrated in the mountainous watersheds from Millard and Sanpete Counties southward to the Pine Valley Mountains and Washington County and the headwaters of the Sevier River in Iron and Garfield Counties. The mountainous portions of Tooele and Juab Counties have been included as seeding target areas since 1988. The intended target areas of this program generally include terrain above 7,000 feet elevation. The Southern and Central Utah Seeding Program utilizes approximately 70 ground-based, manually-operated (Cloud Nuclei Generator, or CNG) sites, containing a 2% silver iodide solution. The goal of the seeding program is to augment wintertime snowpack/precipitation over the seeded watersheds. Cost sharing for the seeding program is provided by the Utah Division of Water Resources, and additional funds from the Lower Colorado River Basin States has resulted in early-season (November 1st-15th) and late season (March 16th– April 15th) extensions to the seeding program since 2010. Precipitation and snowfall were generally near normal during the 2019-2020 winter season, with the higher totals generally observed in far southern Utah. A total of 3,602.25 CNG hours were conducted during 18 storm periods for the core program this season, out of a maximum budgeted 6,500 hours. An additional 1,376.75 hours of seeding were conducted during 9 storm periods for the late-season Lower Basin Extension. There were no seeding suspensions during the 2019-2020 season.

A total of 25 winter seasons of cloud seeding have been conducted in portions of the western Uinta Range in Utah. The Western Uintas program utilizes 12 ground-based, manually-operated (Cloud Nuclei Generator, or CNG) sites, containing a 2% silver iodide solution. The areas targeted for seeding have included the upper portions of both the Weber River and the Provo River drainages in most years. Precipitation and snowfall were below normal during the 2020-2021 winter season, with snow water equivalent for the Weber-Ogden River basin averaging about 74% of the median value on April 1st. The water year precipitation through April 1st averaged 67% of the normal (mean value) across the basin. The Provo River basin had corresponding April 1st averages of 78% of median snowpack and 71% of mean precipitation. A total of 1272.75 CNG hours were conducted during 19 storm periods this season, out of a maximum budgeted 2,500 hours. There was one seeding suspension during the 2020-2021 season, on February 16th due to extreme avalanche danger. Evaluations of the effectiveness of the cloud seeding program were made for both the past winter season and for the 26 seeded winter seasons combined. These evaluations utilize SNOTEL records collected by the Natural Resources Conservation Service (NRCS) at selected sites within and surrounding the seeded target area. Analyses of the effects of seeding on target area precipitation and snow water content have been conducted for this seeding program, utilizing target/control comparison techniques. Multi-season target vs. control evaluations have been performed to compare seasonal performance of the target area in comparison to the control areas during both seeded and non-seeded years. These studies have evaluated the performance of two variables related to seasonal storm productivity, namely total seasonal precipitation and April 1 snowpack (measured in inches of liquid water equivalence). Due to the short period of measurement for total preci

2019-2020 cloud seeding activities in Utah.

Utah has been cloud seeding since the early 1950s to help augment the state's water supply. The Cloud Seeding Act of 1973 gave authority to the Utah Division of Water Resources to oversee state cloud seeding projects. Ground-based seeders shoot silver iodide into winter clouds where it helps form ice crystals. The seeders are placed along foothills and higher elevations where the release of the cloud seeds is timed so that air currents carry them high into the cloud. This process is effective because clouds are formed by water vapor and dust. Under certain natural conditions those water droplets will freeze together around the dust or other particles and, when heavy enough, will fall from the sky as snow. Often, there is more snow that can fall but limited by the number of particles around which ice crystals can form. That is why adding particles, or seeds, facilitates and accelerates the process which may lead to more snow falling than would have under natural conditions. Since snowpack is Utah's largest reservoir, increasing the amount of snow that falls is a win for the water supply. It doesn't work just anywhere. The conditions have to be right. Luckily, Utah's topography, climate and reservoirs make winter snowpack enhancement cost-effective. Statistical analysis shows an average increase in precipitation of 5-15% in seeded areas at a cost of about $2.18 per acre-foot for the additional water. The field program runs November to April and is funded jointly by the state and local water interests. Conditions must be suitable for cloud seeding. Cloud seeding can only occur when there is sufficient water in the atmosphere, which is why Utah's cloud seeding takes place only in the winter. (The summer months are often too dry and don't have enough clouds to seed.) The Division is authorized by the Utah Legislature to split costs with local sponsors up to a maximum of $350,000 per year. There is insufficient funding or local support for a summer seeding program and Uta

Utah has been cloud seeding since the early 1950s to help augment the state's water supply. The Cloud Seeding Act of 1973 gave authority to the Utah Division of Water Resources to oversee state cloud seeding projects. Ground-based seeders shoot silver iodide into winter clouds where it helps form ice crystals. The seeders are placed along foothills and higher elevations where the release of the cloud seeds is timed so that air currents carry them high into the cloud. This process is effective because clouds are formed by water vapor and dust. Under certain natural conditions those water droplets will freeze together around the dust or other particles and, when heavy enough, will fall from the sky as snow. Often, there is more snow that can fall but limited by the number of particles around which ice crystals can form. That is why adding particles, or seeds, facilitates and accelerates the process which may lead to more snow falling than would have under natural conditions. Since snowpack is Utah's largest reservoir, increasing the amount of snow that falls is a win for the water supply.It doesn't work just anywhere. The conditions have to be right. Luckily, Utah's topography, climate and reservoirs make winter snowpack enhancement cost-effective. Statistical analysis shows an average increase in precipitation of 5-15% in seeded areas at a cost of about $2.18 per acre-foot for the additional water. The field program runs November to April and is funded jointly by the state and local water interests.Conditions must be suitable for cloud seeding. Cloud seeding can only occur when there is sufficient water in the atmosphere, which is why Utah's cloud seeding takes place only in the winter. (The summer months are often too dry and don't have enough clouds to seed.)The Division is authorized by the Utah Legislature to split costs with local sponsors up to a maximum of $350,000 per year. There is insufficient funding or local support for a summer seeding program and Utah's

In many past winter seasons, cloud seeding has been conducted in several different regions within central and southern Utah. Since the mid-1970s seeding has been concentrated in the mountainous watersheds from Millard and Sanpete Counties southward to the Pine Valley Mountains and Washington County and the headwaters of the Sevier River in Iron and Garfield Counties. The mountainous portions of Tooele and Juab Counties have been included as seeding target areas since 1988. The intended target areas of this program generally include terrain above 7,000 feet elevation. The Southern and Central Utah Seeding Program utilizes approximately 70 ground-based, manually-operated (Cloud Nuclei Generator, or CNG) sites, containing a 2% silver iodide solution. The goal of the seeding program is to augment wintertime snowpack/precipitation over the seeded watersheds. Cost sharing for the seeding program is provided by the Utah Division of Water Resources, and additional funds from the Lower Colorado River Basin States has resulted in early-season (November 1st-15th) and late season (March 16th– April 15th) extensions to the seeding program since 2010. Precipitation and snowfall were generally near normal during the 2019-2020 winter season, with the higher totals generally observed in far southern Utah. A total of 3,602.25 CNG hours were conducted during 18 storm periods for the core program this season, out of a maximum budgeted 6,500 hours. An additional 1,376.75 hours of seeding were conducted during 9 storm periods for the late-season Lower Basin Extension. There were no seeding suspensions during the 2019-2020 season.

Since the publication of the Utah State Water Plan in 1990, the Utah Division of Water Resources has prepared a detailed summary of Utah’s municipal and industrial (M&I) water every 5 years. This effort includes the quantification of both potable (drinking) and non-potable (secondary) M&I water supplies and uses for community, non-community, self-supplied industries and private domestic water systems. The Division of Water Resources has summarized all M&I data for each of the hydrologic basins in this statewide summary for quick and access information about M&I water use.

A review of duties and funding programs of the Division and Board of Water Resources.

2019-2020 cloud seeding activities in Utah.

Utah has been cloud seeding since the early 1950s to help augment the state's water supply. The Cloud Seeding Act of 1973 gave authority to the Utah Division of Water Resources to oversee state cloud seeding projects. Ground-based seeders shoot silver iodide into winter clouds where it helps form ice crystals. The seeders are placed along foothills and higher elevations where the release of the cloud seeds is timed so that air currents carry them high into the cloud. This process is effective because clouds are formed by water vapor and dust. Under certain natural conditions those water droplets will freeze together around the dust or other particles and, when heavy enough, will fall from the sky as snow. Often, there is more snow that can fall but limited by the number of particles around which ice crystals can form. That is why adding particles, or seeds, facilitates and accelerates the process which may lead to more snow falling than would have under natural conditions. Since snowpack is Utah's largest reservoir, increasing the amount of snow that falls is a win for the water supply. It doesn't work just anywhere. The conditions have to be right. Luckily, Utah's topography, climate and reservoirs make winter snowpack enhancement cost-effective. Statistical analysis shows an average increase in precipitation of 5-15% in seeded areas at a cost of about $2.18 per acre-foot for the additional water. The field program runs November to April and is funded jointly by the state and local water interests. Conditions must be suitable for cloud seeding. Cloud seeding can only occur when there is sufficient water in the atmosphere, which is why Utah's cloud seeding takes place only in the winter. (The summer months are often too dry and don't have enough clouds to seed.) The Division is authorized by the Utah Legislature to split costs with local sponsors up to a maximum of $350,000 per year. There is insufficient funding or local support for a summer seeding program and Uta

Utah has been cloud seeding since the early 1950s to help augment the state's water supply. The Cloud Seeding Act of 1973 gave authority to the Utah Division of Water Resources to oversee state cloud seeding projects. Ground-based seeders shoot silver iodide into winter clouds where it helps form ice crystals. The seeders are placed along foothills and higher elevations where the release of the cloud seeds is timed so that air currents carry them high into the cloud. This process is effective because clouds are formed by water vapor and dust. Under certain natural conditions those water droplets will freeze together around the dust or other particles and, when heavy enough, will fall from the sky as snow. Often, there is more snow that can fall but limited by the number of particles around which ice crystals can form. That is why adding particles, or seeds, facilitates and accelerates the process which may lead to more snow falling than would have under natural conditions. Since snowpack is Utah's largest reservoir, increasing the amount of snow that falls is a win for the water supply. It doesn't work just anywhere. The conditions have to be right. Luckily, Utah's topography, climate and reservoirs make winter snowpack enhancement cost-effective. Statistical analysis shows an average increase in precipitation of 5-15% in seeded areas at a cost of about $2.18 per acre-foot for the additional water. The field program runs November to April and is funded jointly by the state and local water interests. Conditions must be suitable for cloud seeding. Cloud seeding can only occur when there is sufficient water in the atmosphere, which is why Utah's cloud seeding takes place only in the winter. (The summer months are often too dry and don't have enough clouds to seed.) The Division is authorized by the Utah Legislature to split costs with local sponsors up to a maximum of $350,000 per year. There is insufficient funding or local support for a summer seeding program and Uta

In many past winter seasons, cloud seeding has been conducted in several different regions within central and southern Utah. Since the mid-1970s seeding has been concentrated in the mountainous watersheds from Millard and Sanpete Counties southward to the Pine Valley Mountains and Washington County and the headwaters of the Sevier River in Iron and Garfield Counties. The mountainous portions of Tooele and Juab Counties have been included as seeding target areas since 1988. The intended target areas of this program generally include terrain above 7,000 feet elevation. The Southern and Central Utah Seeding Program utilizes approximately 70 ground-based, manually-operated (Cloud Nuclei Generator, or CNG) sites, containing a 2% silver iodide solution. The goal of the seeding program is to augment wintertime snowpack/precipitation over the seeded watersheds. Cost sharing for the seeding program is provided by the Utah Division of Water Resources, and additional funds from the Lower Colorado River Basin States has resulted in early-season (November 1st-15th) and late season (March 16th– April 15th) extensions to the seeding program since 2010. Precipitation and snowfall were generally near normal during the 2019-2020 winter season, with the higher totals generally observed in far southern Utah. A total of 3,602.25 CNG hours were conducted during 18 storm periods for the core program this season, out of a maximum budgeted 6,500 hours. An additional 1,376.75 hours of seeding were conducted during 9 storm periods for the late-season Lower Basin Extension. There were no seeding suspensions during the 2019-2020 season.

Since the publication of the Utah State Water Plan in 1990, the Utah Division of Water Resources has prepared a detailed summary of Utah’s municipal and industrial (M&I) water every 5 years. This effort includes the quantification of both potable (drinking) and non-potable (secondary) M&I water supplies and uses for community, non-community, self-supplied industries and private domestic water systems. The Division of Water Resources has summarized all M&I data for each of the hydrologic basins in this statewide summary for quick and access information about M&I water use.

A review of duties and funding programs of the Division and Board of Water Resources.

The Utah Climate Center (UCC) has completed its evaluation of cloud seeding conditions over the mountains of Utah, identifying potential improvements in several long-running programs aimed at increasing snow accumulation across the state. Through the creation of multiple cross-sections over different mountain ranges, the center offers the Utah-Focused Forecasting Model, a tool for ascertaining the primary variables for cloud seeding — temperature and the presence of supercooled liquid water — over most of the state’s mountains, providing guidance for seeding operations.

This report documents proposed Snow Water Equivalent (SWE) indices-based cloud suspension criteria derived from seasonal streamflows and observed SWE values of SNOTEL stations in cloud seeding projects in the State of Utah. The objectives of this report are: (1) review and summarize the cloud seeding suspension criteria practiced in Utah and neighboring states of Utah such as Colorado, California, and Nevada; (2) evaluate the existing SWE based indices and establish a relationship between the SWE and streamflow in the cloud seeding projects; and (3) update and recommend cloud seeding suspension criteria in the project areas.

The Utah Climate Center (UCC) has completed its evaluation of cloud seeding conditions over the mountains of Utah, identifying potential improvements in several long-running programs aimed at increasing snow accumulation across the state. Through the creation of multiple cross-sections over different mountain ranges, the center offers the Utah-Focused Forecasting Model, a tool for ascertaining the primary variables for cloud seeding — temperature and the presence of supercooled liquid water — over most of the state’s mountains, providing guidance for seeding operations.

This report documents proposed Snow Water Equivalent (SWE) indices-based cloud suspension criteria derived from seasonal streamflows and observed SWE values of SNOTEL stations in cloud seeding projects in the State of Utah. The objectives of this report are: (1) review and summarize the cloud seeding suspension criteria practiced in Utah and neighboring states of Utah such as Colorado, California, and Nevada; (2) evaluate the existing SWE based indices and establish a relationship between the SWE and streamflow in the cloud seeding projects; and (3) update and recommend cloud seeding suspension criteria in the project areas.

Cloud seeding initially began in Utah in the early 1950's, and in 1973, the legislature passed the Utah Cloud Seeding Act that determined the ownership of water to be considered as part of Utah's basic water supply. The Cloud Seeding Act of 1973 also gave the authority to the Utah Division of Water Resources to be the only entity to license contractors and permit cloud seeding projects in the state of Utah.

Cloud seeding initially began in Utah in the early 1950's, and in 1973, the legislature passed the Utah Cloud Seeding Act that determined the ownership of water to be considered as part of Utah's basic water supply. The Cloud Seeding Act of 1973 also gave the authority to the Utah Division of Water Resources to be the only entity to license contractors and permit cloud seeding projects in the state of Utah.

A poster submitted in ENG 207 taught by Dr. David Prescott for the Fall 2016 semester., In the recent years temperature has been rising noticeably in the UAE. The raise of temperature has been causing a raise of humidity level. Artificial mountains can be built to decrease the humidity level and promote precipitation. Orographic precipitation is the type of precipitation used with artificial mountains. How can building artificial mountains increase orographic precipitation and how to build such mega structure.

Dans les conditions humides, l'avènement de couronne sur les lignes de transmission haute tension pourrait aboutir à la vibration des conducteurs. Ce type de vibration, connu comme "Vibration induite par effet de couronne", peut conduire à la fatigue des conducteurs et leurs éléments de support. Il a été établi que la présence intermittente de la charge d'espace de couronne et du vent ionique sont les causes principales de ce phénomène. L'objectif principal de ce mémoire de maîtrise est la simulation numérique et expérimentale sur deux conducteurs courts, l'un lisse et l'autre toronné. Pour la partie expérimentale, notre approche est basée sur un modèle physique déjà employé dans les travaux précédents du GRIEA "Groupe de Recherche de l'Ingénierie de l'Environnement Atmosphérique". Ce modèle utilise un conducteur placé au centre d'un cylindre en grillage métallique. Ce dispositif a permis d'étudier l'influence des différents facteurs sur les vibrations des conducteurs haute tension placés sous la pluie artificielle. Les résultats des simulations expérimentales seront appliqués au modèle numérique en vue d'effectuer les simulations numériques. La méthode des éléments finis a été utilisée pour développer le modèle numérique. En vue de valider un modèle pratique avec les résultats expérimentaux, deux modèles numériques ont été développés. Le premier modèle, considéré comme modèle de base est développé pour un conducteur lisse, alors que le deuxième, appliqué au conducteur toronné, a pour but de compléter le modèle de base. Les entrées pour ces deux modèles numériques sont appliquées au logiciel COSMOS et les simulations ont été exécutées. Les forces impliquées dans la constitution des gouttes d'eau et leur éjection d'un conducteur haute tension seront modélisées numériquement en utilisant les résultats des travaux de recherches précédents et en sélectionnant la meilleure combinaison de ces forces. Les résultats expérimentaux sont utilisés pour évaluer la précision des