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Devising effective strategies to retard the negative impacts of extreme climatic events on water security in general and environmental water balance in specific is imperative, especially in semi-arid rural-Western-India, where climate change has markedly increased water scarcity in domestic and agricultural sectors. This exploratory research thus aimed at investigating the water budget against mismanagement of available water resources for remote-marginalized villages in rural-Nashik (West-India). Investigation entailed visual interpretation of LULC analysis (2008–2017) using fine-scale Google Earth imageries, rainfall-runoff analysis using SCS-CN method, determining the supply-demand potential of water storage structures using field-experimentations and PRA tools, and estimation of season-wise water-budget using hydrological (water-balance) equations. Results identified agriculture as the major land-use (~ 78%) followed by hilly regions (~ 16%) and water bodies (~ 3%). Surface runoff was found as the dominating hydrological phenomenon (33–89% of monsoonal rainfall) followed by surface storage (6–36% of annual rainfall) and groundwater flow (4–82% of annual rainfall). Deforestation over hills for firewood, which reduced forest cover by 52%, was observed as the primary concern for soil erosion, thereby siltation of water bodies and higher runoff against percolation. Erratic rainfall patterns (departure range − 42 to 83% during 1998–2017) coupled with sub-graded irrigational systems confined the agricultural practices to one season [South–West monsoon (June–September)]. High unmet drinking water demand (73% to 98%) forced women communities to fetch water by walking 4.5 ± 1.5 km. Considering the urgent response to collectively combat water-budget imbalance, integrated water security plans were proposed using decentralized participatory watershed development approaches. [ABSTRACT FROM AUTHOR]

The Huacachina oasis, on Peru’s south-central coast, is an important tourism hotspot, driving economic activity in the Ica region. However, its natural sustainability has been compromised by aquifer overexploitation, leading to a decline in the water table. Currently, it is grappling with water recharge challenges, and has been resorting to methods such as recharging water from wells. Despite its importance, there have been few studies of the water balance at the Huacachina oasis. The aim of this study was to investigate the hydrological balance of the oasis, scrutinizing both water losses and gains, including evaporation, infiltration and inflows. Over a 72-hour period, precipitation, water level fluctuations and inflow rates were recorded and validated. Evaporation was indirectly computed using the Penman method, which is known for its efficacy. The oasis's storage capacity was assessed using detailed bathymetric and topographic surveys. The study identified the lowest bottom elevation at 401.488 m.a.s.l., the highest at 404.194 m.a.s.l., and a storage capacity of 35,813 m3. Our results showed precipitation had no impact on water supply, with the main source being well water pumped from underground. Water losses were due mainly to evaporation and infiltration. Daily evaporation averaged 7.7 mm, while the infiltration rate stood at 0.55 mm/hr. Infiltration exceeded evaporation by 1.7 times (63.4% vs. 36.6%). A water imbalance of 11.5 % was identified, with water inflows exceeding outflows, probably due to leaks in water and sewage systems. Unlike previous research, this study provides a detailed temporal analysis of Huacachina oasis water dynamics; however, in the future additional research will be required to address limitations. Our study also emphasizes the need to explore hidden water sources (leaks in water and sewage networks), in order to address improved oasis management and the effects of climate change, and to ensure sustainability.

Climate change is presently a widely discussed subject in relation to alterations in water storage capacity and the components of the hydrological balance within catchment areas. This research study was directed at two main objectives: 1. The indirect estimation of long-term mean annual runoff using an empirical model; 2. The determination of changes in the annual runoff regime of fifty Danube sub-basins. Monthly areal precipitation, discharges, and air temperature data from 1961 to 1990 were collected for selected headwater sub-basins of the Danube River. In the first part, Turc-type empirical equations for the estimation of the long-term average annual runoff R in the Danube basin were employed. The parameters of the empirical equations were determined through nonlinear regression. Given the underestimation of the actual (territorial, balance) evapotranspiration ET values determined from the balance equation, the precipitation totals were corrected by +10%. With a 10% increase in precipitation, the values of balance ET reached the values ET determined by the Budyko–Zubenok–Konstantinov method. In the second part, fifty equations for the estimation of changes in the average annual runoff, depending on increases in the air temperature and changes in the annual precipitation separately for each of the 50 sub-basins, were established. In conclusion, the results suggest that, on average, a 100 mm increase in the average annual rainfall in the Danube River headwater sub-basins, will cause a 50 mm increase in outflow, and a 1 °C increase in the average annual air temperature will lead to a 12 mm decrease in runoff.

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Potential changes in a hydrological regime caused by a changing climate represent a crucial source of uncertainty in water resources management. For example, in Slovakia, they may manifest themselves in a decrease in water resources, a change in the seasonality of runoff, and an increase in the extremes of floods and droughts. The research presented here focuses on using the hydrological balance equation to predict changes in the total catchment evapotranspiration under changing climate conditions. Using the TUW rainfall-runoff model and the KNMI and MPI climate change scenarios, the hydrological regime of eight selected basins in Slovakia was simulated for three thirty-year periods from 2010 until the year 2100. The results showed that the growth of total catchment evapotranspiration observed in recent decades is likely to increase further in the future.

Due to a changing climate, likely changes to a hydrological regime are one of the primary sources of uncertainty to consider in managing water resources. In Slovakia, a decline in the country’s water resources, combined with a change in the seasonality of runoff and an increase in the extremeness of floods and droughts, represents a potential threat. The objective of the paper was to explore trends in the components of the long-term hydrological balance of various river basins to detect the impacts of changing climate conditions along the Western Carpathians. The proposed method is a comparative exploratory analysis of the hydrological balance of the selected river basins. Temporal changes in the catchments’ average air temperatures, precipitation, runoff, and their differences (considered as an index of the actual evapotranspiration), were estimated for 49 years of data; two non-overlapping sub-periods (25 and 24 years) in the seven river basins were also compared. This work also aims at evaluating the applicability of gridded inputs from the CarpatClim database for modelling the hydrological balance over an extended period. The results document the impact of the rising air temperature and, in part, local physiographic factors on the changes in runoff and actual catchment evapotranspiration.

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Copyright of Grundwasser is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In semiarid regions, dams are useful for surface water storage, sediment sequestration, and aquifer recharge. Built in 1987 on the Cap Bon peninsula (in northeastern Tunisia), the Lebna Dam is considered a good example of a multifunctional reservoir. The dam feeds two important irrigation networks, stores large sediment quantities, and allows a significant recharge flow to the underlying aquifer. This work suggests new leakage flow and dam–aquifer interaction characterizations through the development of an approach that combines a water balance calculation, geological field observations, groundwater monitoring, and geophysical research. The hydrological balance calculation performed over the monitoring period (1990–2017) shows that an estimated water volume of 3.7 mm3 year−1 has leaked from the Lebna reservoir to the coastal aquifer. Geological mapping of the Lebna Dam basin in summer 2019 revealed the existence of permeable layers of sands to sandstones exposed along the southern banks of the reservoir and extending to an elevation that included the water level when the dam is full; these rocks outcrop at approximately 16 m.a.s.l. A geophysical survey based on 67 vertical electrical soundings and 8 electrical resistivity tomography profiles in the area downstream of the reservoir was carried out to identify the lateral continuity of the recharge zones. Piezometric campaigns consisting of four field surveys in 2019 and 2020 were conducted in the region downstream of Lebna Dam, consisting of 71 water well samples. The collected evidence led to the conclusion that concentrated recharge occurs in the downstream bank of the dam. [ABSTRACT FROM AUTHOR]

Švihov dam, the largest drinking water source in the Czech Republic and Central Europe, has problems with eutrophication. The Švihov dam catchment spreads over 1200 km2 and supplies over 1.5 million people in the capital of Prague and the Central Bohemian region with drinking water. Due to intensive agricultural activities and a lack of wastewater treatment plants in small settlements, the water quality is deteriorating. As a result, corrective measures need to be taken. Technological Agency of the Czech Republic supported this research which proposes different scenarios for a reduction of water quality degradation in the dam. The Trnávka dam watershed was chosen for study purposes as it occupies one quarter of the Švihov dam watershed. Hydrological balance was established using measured data. Point and non-point sources of nutrients were determined by field research and included in a Soil and Water Assessment Tool (SWAT) model. This study aims to propose complex watershed management to improve the state of the environment in the entire area and to reduce eutrophication. Different management practices would reduce nutrient loads of streams and increase water quality which is the critical factor in dam eutrophication. This research brings methodology and systematic approach to integrated management, and can be applied not only for the Švihov dam, but also for other watersheds, including those which function as drinking water supply.

The steppe of northern Tierra del Fuego is an important region for studying climate variability in the Southern Hemisphere, due to its position at the southern margin of the Southern Hemisphere Westerly Wind belt. Here we present a multiproxy analysis of a sedimentary sequence from Laguna Carmen (53°S, 68°W) which provides evidence of the progressive aridity and strengthening of the low-level Westerlies during the Late Holocene. We identified three prominent phases in the climatic record from Laguna Carmen: a cold and wet period between ~4000 cal. BP and ~2200 cal. BP, evidenced by a relative high lake level, periodic runoff into the lake, and oligohaline (mean: 2554 μS/cm) salinities; a step-change towards warmer and drier conditions after ~2200 cal. BP, reflected by limited runoff and oligo-mesohaline salinities (mean: 4799 μS/cm); and finally, the establishment of modern semi-arid conditions some time after ~1000 cal. BP, when the lake became a shallow lake that sometimes dried out during the summer. Our results coincide with paleoclimatic numerical models that suggest a progressive aridification of the southern Patagonian steppe since 6000 cal. BP due to stronger Westerlies and higher temperatures associated with changes in solar irradiance. [ABSTRACT FROM AUTHOR]

This study presents the impact of global warming on precipitation patterns in Ilorin, Nigeria, and its implications on the hydrological balance of the Awun basin under the prevailing climate conditions. The study analyzes 39 years of rainfall and temperature data of relevant stations within the study areas. Simulated data from the Coupled Global Climate model for historical and future datasets were investigated under the A2 emission scenario. Statistical regression and a Mann-Kendall analysis were performed to determine the nature of the trends in the hydrological variables and their significance levels, while a Soil and Water Assessment Tool (SWAT) was used to estimate the water balance and derive the stream flow and yield of the Awun basin. The study revealed that while minimum and maximum temperatures in Ilorin are increasing, rainfall is generally decreasing. The assessment of the trends in the water balance parameters in the basin indicates that there is no improvement in the water yield as the population increases. This may result in major stresses to the water supply in the near future.

Sediment deposition is an issue affecting many rivers. To oppose it, sediment withdrawals are often used. However, this practice can trigger further problems in river and coastal sections but, on the other hand, periodic removal of deposited sediments can reduce flooding risk. Also, these sediments can be used for beach nourishment. Therefore, before carrying out a sediment withdrawal, it is necessary to analyze the whole basin to evaluate the consequences for the sediment balance. This paper describes a methodology to evaluate the effects of river sediment withdrawals through a case study on the Amendolea River, a torrential river in southern Italy. In particular, the methodology is divided into three main phases. The first phase was developed with GIS software in order to perimeter and to morphometrically characterize the river basin and its hydraulically and sedimentologically homogeneous sub-basins. The second phase was developed using the HEC-HMS software in order to evaluate the hydrological balance of the basin and its sub-basins. The last phase was developed using the HEC-RAS software (through the SIAM model) in order to identify the areas in erosion, in deposition and in equilibrium. Moreover, through this model is possible to identify the sections where sediments can be withdrawn, and to estimate the possible morphological river changes due to withdrawals. In this case study, the sediments will be taken from the sections where the bottom has elevations near or above those of adjacent lands, such as to increase the flooding risk. Sediment withdrawals will be taken without eroding the bottom and at a distance from the river banks that does not unstabilize them. Finally, the methodology described in this paper is based on the joint use of various open source software and can be used in any other river with hydrological regime similar to the Amendolea River. [ABSTRACT FROM AUTHOR]

Copyright of Tecnología y Ciencias del Agua is the property of Instituto Mexicano de Tecnologia del Agua (IMTA) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Background: The páramo provides key ecosystem services, including regulation and provision of water. To understand the underlying functions, an ecosystem approach is necessary. Aims: We quantified the combined effect of vegetation and soils (integrated topographic and vegetation units – TVU) on the hydrological balance of a Venezuelan páramo micro-watershed and analyse its hydrological response to intra- and interannual rainfall variability. Methods: Data (2008–2016) from meteorological stations of TVUs and of a streamflow station was used to calculate watershed level hydrologic balances. We quantified the impact of the TVUs outputs by calculating evapotranspiration under non-standard conditions (ETc adj). Result: Evapotranspiration of wetlands and tarns was high, exceeding annual precipitation. Shrubland had low evapotranspiration. Recharge of páramo reservoirs (soils, wetlands, tarns) occurred when monthly rainfall exceeded 90 mm. In dry years there were lower water yields with less effective hydrological regulation. In average years the differences between input and output in watershed balances were very small. Conclusions: The high and constant evapotranspiration of the wetlands and tarns (due to permanent water availability) suggests they could maintain streamflow during dry periods. Their high evapotranspiration rates are compensated by low rates in shrublands units, reducing the mean total evapotranspiration of the watershed. The watershed balances suggest a limited regulatory capacity in these relatively dry páramos with no volcanic soils. [ABSTRACT FROM AUTHOR]

The relationship between rainfall and runoff is a complex phenomenon and understanding the physical processes, hydrological components and their impacts on response of watershed to precipitation is one of the challenging issues in watershed hydrology and planning. There is still a need to improve conceptual hydrological models in water scarce regions, such as Iran mainly because in many cases there is not enough data to fully describe this phenomenon. In this research, we aimed to present an improved and parsimonious framework that increases the performance of a conceptual model in water balance and discharge modeling for Delichay watershed located in Hablehroud basin, Iran as one of the main source of water supply for downstream fertile agricultural areas that produce a considerable amount of cereals and play a major role for food and water security of the region. In areas where data for water cycle components are not available or limited, it is recommended to use parsimonious approach in order to have an acceptable level of understanding of the system with minimum possible predictor variables. The Salas model used in current research to model water balance over the period 1983–2012 and evaluation of the results indicated an unsatisfactory performance when the entire period was modeled altogether (NSE = 0.35, d = 0.70, R2 = 0.63, RSR = 0.80, PBIAS = 4.96 and RMSE = 41.87). A key reason is that this watershed is intensively impacted by human activities and homogeneity analysis confirmed a sudden shift in runoff data during 1998–1999. Such a sudden shift reveals the role of human activities impacts on the watershed with a total reduction of 58 mm of runoff per year while the climate variability has not occurred in the region. Thus, the entire period (i.e. 1983–2012) was divided into two homogenous sub-periods of before and after the change point (i.e., pre-change and post-change periods). The results indicated that modeling performance in the sub-periods improved (e.g. the NSE was 0.77 and 0.66 for pre-change and post-change, respectively, vs. 0.35 for entire period). Meanwhile, it is revealed that water balance affected by human activities over the time and application of historical data for water balance modeling cannot be reliable without considering the homogeneous data. Since, many watersheds in the world have been affected by human activities or climate variability, it is recommended to consider the homogeneity of observed data before any application. [ABSTRACT FROM AUTHOR]

Švihov dam, the largest drinking water source in the Czech Republic and Central Europe, has problems with eutrophication. The Švihov dam catchment spreads over 1200 km2 and supplies over 1.5 million people in the capital of Prague and the Central Bohemian region with drinking water. Due to intensive agricultural activities and a lack of wastewater treatment plants in small settlements, the water quality is deteriorating. As a result, corrective measures need to be taken. Technological Agency of the Czech Republic supported this research which proposes different scenarios for a reduction of water quality degradation in the dam. The Trnávka dam watershed was chosen for study purposes as it occupies one quarter of the Švihov dam watershed. Hydrological balance was established using measured data. Point and non-point sources of nutrients were determined by field research and included in a Soil and Water Assessment Tool (SWAT) model. This study aims to propose complex watershed management to improve the state of the environment in the entire area and to reduce eutrophication. Different management practices would reduce nutrient loads of streams and increase water quality which is the critical factor in dam eutrophication. This research brings methodology and systematic approach to integrated management, and can be applied not only for the Švihov dam, but also for other watersheds, including those which function as drinking water supply. [ABSTRACT FROM AUTHOR]

This paper follows the description of the physico-geographic natural setting from the Razim-Sinoe lagoon complex area and the detailed presentation of its characteristics. The tasks of the study are determined by the achievement of goals by conducting a series of data and information analyzes, consulting a number of specialized sources in the field of geography. The statistical data and graphs present in the paper were processed after the Meteorological Center Dobrogea Litoral and the Dobrogea Seaside Basin Administration. Materials and studies were also carried out by Geoecomar, but also by the Danube Delta Biosphere Administration, given the complexity of the complex. The interpretation of the obtained information and data is presented by the analysis method, being represented by interpretations, maps, graphs, tables, statistical data representing the product of the research, indicating the role of the elements in the structure of the whole work. Given the large expanse and geographical position of the lagoon complex, the hydric and physico-chemical regimes have certain peculiarities. Due to its peculiarities, the very diverse fauna and flora present in the Razim-Sinoe complex, it can be said that it is one of the main tourist attractions in the area. [ABSTRACT FROM AUTHOR]

Highlights • Large basins are homes to millions of people who depend on water for survival. Water drives the economic engine. • Use of publicly available model output and satellite data. • Analysis of extreme events: droughts and floods. Abstract Numerous large river basins of the world have few and irregular observations of the components of the terrestrial hydrological cycle with the exception of stream gauges at a few locations and at the outlet along with sparsely distributed rain gauges. Using observations from satellite sensors and output from global land surface models, it is possible to study these under-observed river basins. With populations greater than a billion people, some of these rivers (e.g., the Ganga-Brahmaputra, the Yangtze, the Nile and the Mekong) are the economic engines of the countries they transect, yet thorough assessment of their flow dynamics and variability in regard to water resource management is still lacking. In this paper, we use soil moisture (0–2 m) and surface runoff from the NASA Global Land Data Assimilation System (GLDAS), evapotranspiration, and Normalized Difference Vegetation Index (NDVI) from the Moderate Resolution Imaging Spectroradiometer (MODIS) and rainfall from the Tropical Rainfall Measuring Mission (TRMM) and total water storage anomaly from the Gravity Recovery and Climate Experiment (GRACE) to examine variability of individual water balance components. To this end, understanding the inter-annual and intra-seasonal variability and the spatial variability of the water balance components in the major river basins of the world will help to plan for improved management of water resources for the future. [ABSTRACT FROM AUTHOR]

Determining an optimal calibration strategy for hydrological models is essential for a robust and accurate water balance assessment, in particular, for catchments with limited observed data. In the present study, the hydrological model Bilan was used to simulate hydrological balance for 20 catchments throughout the Czech Republic during the period 1981–2016. Calibration strategies utilizing observed runoff and estimated soil moisture time series were compared with those using only long-term statistics (signatures) of runoff and soil moisture as well as a combination of signatures and time series. Calibration strategies were evaluated considering the goodness-of-fit, the bias in flow duration curve and runoff signatures and uncertainty of the Bilan model. Results indicate that the expert calibration and calibration with observed runoff time series are, in general, preferred. On the other hand, we show that, in many cases, the extension of the calibration criteria to also include runoff or soil moisture signatures is beneficial, particularly for decreasing the uncertainty in parameters of the hydrological model. Moreover, in many cases, fitting the model with hydrological signatures only provides a comparable fit to that of the calibration strategies employing runoff time series.

Abstract This paper studies the hydraulic performance of two swales composed of filters for stormwater management (filtering swales) in a large-scale experimental study and compares them to the performance of a swale composed of traditional bioretention soil (bioswale). Using experimental data, dimensionless formulations are derived to reflect the influence of swale design parameters on hydraulic performance. The developed formulas can be used to design swales accounting for practical factors for decision makers such as local rainfall patterns, volume capture requirements, and drainage area. The experimental data show that while the bioswale is characterized by large overland flows, the tested filtering swales manage, in the majority of cases, the complete inflow volume without overland flow. The longitudinal slope of the swales does not affect the infiltration capacity of the filtering swales for the tested experimental boundary conditions, only the inflow rate and media water content are found to be statistically significant. As an example, filtering swales tested in this study captured 90% of the runoff generated by a 12.2 mm/h storm (approximately a 5-year return period 1-h duration storm event in the city of Trondheim) on a road 40 times larger than the swale. This highlights the capacity of such swales for handling infrequent events. Highlights • Filtering swales showed better hydrological response than the bioswale. • Filtering swales are able to handle infrequent events such as 10-year return period. • Longitudinal slope showed no impact on the hydrological response of filtering swales. • Empirical relationships are proposed for dimensioning filtering swales. [ABSTRACT FROM AUTHOR]

In spite of recent progresses in evaporation estimate through advanced models and laboratory experiments, the drying process of bare soils through its successive stages remains difficult to predict. A study which addresses evaporation modeling in natural bare soils is presented. It relies upon hydro-meteorological measurements performed in a plot with a bare silt loam soil maintained in natural conditions. The following steps are involved: estimate of daily actual evaporation, E, through the hydrological balance, scaling with pan evaporation measurements, E, and analysis of the relation of E/E with the soil moisture vertical profile. The results enable us (1) to check the occurrence of the first stage of the evaporation process, characterized by not limited-soil water supply and high evaporative rates, and (2) to identify the transition from the first to the second stage, with decreasing soil water-limited E values. The last point requires the introduction of a soil water content threshold at 5 cm depth, that is associated with the soil field capacity. The adopted procedure provides insights on the soil water dynamics at depths differently involved through the successive stages of the evaporative process. Finally, indications on the use of pan evaporation measurements in evaporative rate estimate at least during the first stage of the process are also given. [ABSTRACT FROM AUTHOR]

Cape Fear is an outdoor 7 × 7 m hillslope laboratory located at the University of Tuscia, Viterbo, Italy, and is equipped with real-time monitoring sensors used to analyse runoff generation. In this paper, hydrological phenomena that occurred during Cape Fear's first 2 years of operation are reported to provide insight into the basic dynamics underlying the hydrological response at the hillslope scale. Based on our findings, surface and subsurface runoff are likely driven by rainfall-threshold phenomena, and evapotranspiration phenomena account for more than 70% of rainfall water input. Future studies will investigate the threshold relationship between rainfall and runoff. [ABSTRACT FROM AUTHOR]

This study was performed to investigate the hydrological and the hydrogeological framework of the Lottenbachtal, Germany. Long-term climatic data were statistically analyzed, water and soil samples were collected and analyzed, stream flow discharge was measured and separated, the hydrological balance of this catchment was calculated and a hydrological and hydrogeological conceptual model was constructed. The study area is characterized mainly by the precipitation value ranged between 0.1 and 5 mm/day. The actual evapotranspiration constitutes 31.90 % of the total precipitation, the direct surface runoff constitutes 61.04 %, the soil storage constitutes 3 % and the groundwater recharge of the Lottenbachtal constitutes only 4 % of the total precipitation. The Lottenbachtal has largely affected the diversity of the land use, which includes forests, arable areas, abandoned coal mines and settlement areas. The soil of the forested area is represented by relatively high acidic conditions and relatively high sulfate concentrations, while the soil of the arable areas is represented by near-neutral conditions associated with relatively high concentrations of nutrients and other chemical elements (calcium, magnesium, sodium, potassium, chloride, sulfate, nitrate). The settlement areas are characterized by huge blocks of concrete and backfills, which are rich in calcium and magnesium carbonates. The effects of this diversity in the land use on groundwater and surface water quality resulting by leaching the chemical elements from the soil covers and the other materials. These effects are represented by the following complex water types of Ca-Na-Mg-Cl-SO4-HCO3, Ca-Mg-HCO3-SO4, Ca-Na- Mg-Cl-SO4, Ca-Na-Mg-Cl-SO4 and Ca-HCO3, which represent the diversity of the flow paths of the water as well as to mixing processes. The diversity of the land use also affected the physical hydrological-hydrogeological characteristics of the study area by increasing the direct surface runoff and decreasing the groundwater recharge. The impervious surfaces of the settlement areas and the low hydraulic conductivities of the soil covers are responsible for these conditions. [ABSTRACT FROM AUTHOR]

Given increasing anthropogenic and climatic pressures on water resources, groundwater and surface water need to be better managed and preserved. As these two water stocks can be connected to each other, their evolutions are linked and need to be considered as such. However, interactions between lakes and groundwater are not well understood and, most of the time, are not taken into account. Therefore, establishing a comprehensive approach to quantify groundwater and lakes' hydrogeochemical interactions in various settings is of foremost importance for assessing the sensitivity of lakes to groundwater evolution. In this study, small kettle lakes set in fluvioglacial deposits and that are most likely well connected to shallow unconfined aquifers are specifically targeted. Geochemistry and isotopic results highlight that groundwater flux to the lakes is generally the dominant parameter of the lake water budget. The Rn results in particular suggest that 38% of the studied lakes have a high proportion of groundwater in their balances. It appears that the different tracers are complementary: geochemistry is influenced by groundwater inflows, reflecting its quality and the local geology, whereas water stable isotopes correspond directly to the volumetric lake water budget, and both of these tracers are impacted by in-lake processes. Moreover, the third tracer considered, Rn, highlights the location of groundwater inputs in space and time. Finally, the studied kettle lakes are characterized by a short to medium flushing time by groundwater. As a result, these lakes can be highly sensitive to environmental and climate changes affecting groundwater. [ABSTRACT FROM AUTHOR]

Increasing impervious land cover has great impacts on groundwater regimes in urbanized areas. Low impact development (LID) is generally regarded as a sustainable solution for groundwater conservation. However, the effects of LID on the spatial-temporal distribution of groundwater are not yet fully understood. In this case study, a coupled Storm Water Management Model (SWMM) and Finite Element Subsurface FLOW system (FEFLOW) model was used to simulate surface and groundwater flow in an urbanized area in Shenzhen, China. After verification, the model was used to analyze the spatial-seasonal variations of groundwater head and hydrological processes under different LID scenarios. The results indicate that if the runoff from 7.5% and 15% of impervious area is treated by LID facilities, the annual surface runoff decreases by 5% and 9%, respectively, and the spatial average groundwater head relative to sea level pressure increases by 0.9 m and 1.7 m in the study area, respectively. The rise in groundwater head generally decreases from the recharge zones to the discharge zones surrounded by the streams and coastal waters. However, the groundwater head change is determined not only by the location in the catchment, but also by the hydraulic conductivity of underlying aquifer and LID infiltration intensity. Moreover, LID significantly enhances groundwater recharge and aquifer storage in the wet seasons; in turn it increases aquifer release and groundwater discharge in the dry seasons. However, LID has the potential to increase the risk of groundwater flooding during wet seasons in areas with poor aquifer drainage capacity and shallow groundwater depth. The findings from this study provide the basis for further assessing the benefit and risk of LID infiltration for groundwater supplementation in the urbanized areas.

Se estudió la distribución del agua lluvia durante tres años en un bosque climácico de roble (Quercus humboldtii) y dos plantaciones forestales, de pino (Pinus patula) y ciprés (Cupressus lusitanica) ubicados en los Andes colombianos. Los principales ingresos de agua al bosque ocurrieron por la lluvia, cuyo valor medio anual fue 1.700 mm año-1. La precipitación interna tuvo la mayor participación de los flujos hídricos del bosque, siendo máxima en el cipresal (1.486 mm a-1, 90 %) y mínima en el pinar (1.389 mm a-1, 81 %), mientras que el escurrimiento cortical fue muy bajo en los tres bosques (1-3 mm a-1, 0,1-0,2 %). La máxima intercepción se presentó en el pinar (329 mm a-1), equivalente al 19 % de la lluvia. A diferencia de estos flujos hídricos del dosel los flujos hídricos del suelo sí mostraron diferencias significativas entre coberturas (P Rainfall distribution was assessed for three years in a mature oak forest (Quercus humboldtii), pine (Pinus patula) and cypress (Cupressus lusitanica) plantations in the northern part of the colombian Andean mountains. An annual average of 1700 mm was the main water input in the forests, which came from the bulk precipitation. The higher water flows were represented by throughfall, which showed a maximum value in the cypress (1486 mm y¹, 90%) and a minimum one in the pine (1389 mm y¹, 81%) plantations, respectively. Stemflow was very low in the three forest types (1-3 mm y¹, 0.1-0.2%). The maximum amount of water intercepted by forest crowns was found in the pine plantation (329 mm y¹), which accounted for 19% out of the total rainfall. In opposition to the patterns found for throughfall and stemflow, soil hydric flows did show significant differences among forest types (P

• Effects of mattic epipedon coverage on surface water conservation capacity were examined. • Declining mattic epipedon cover decreased surface runoff, especially under moderate rainfall. • Increased rainfall and mattic epipedon cover decreased evapotranspiration. • Soil water consumption aggravated with decreasing mattic epipedon coverage under non-rainfall. • Higher mattic epipedon cover maintains higher water conservation capacity under moderate rainfall. The Qinghai-Tibetan Plateau—known as the roof of the world and the water tower of Asia—is facing serious degradation of its ecosystems, with alpine meadows being particularly threatened. However, little is known about how the loss of mattic epipedon (the characteristic topsoil of alpine meadows) alters the water conservation capacity of the region. Here we examined the effects of different mattic epipedon coverages on surface runoff, evapotranspiration, and soil water storage under different rainfall conditions. Our results showed that the surface runoff was significantly higher under moderate rain conditions (P > 10 mm day−1) than under light rain conditions (P < 10 mm day−1), and that declining coverage significantly increased surface runoff, especially under moderate rain conditions. The average evapotranspiration at 90 %, 60 %, and 30 % mattic epipedon coverages were 5.38 mm, 5.88 mm, and 6.38 mm under non-rainfall conditions, and 0.97 mm, 1.60 mm, and 2.24 mm under moderate rain conditions. Meanwhile, mattic epipedon coverage had a positive effect on the supplementation of soil water under moderate rainfall and on the conservation of soil water under non-rainfall conditions. Overall, alpine meadows with higher mattic epipedon coverage were more effective at maintaining surface runoff and improving soil water conservation. These findings highlight the importance of conserving and restoring alpine meadows to improve the water security in the Qinghai-Tibetan Plateau and other downstream regions. [ABSTRACT FROM AUTHOR]

Located on the triple rift junction hosting the Karonga-Usungu depression in Tanzania, Lake Ngozi is the second largest crater lake of the East African Rift. The lake has a number of peculiar features: it has a near constant water level, no permanent surface inlets and outlets, it is vertically well-mixed, with homogeneous distribution of temperature and chemical composition, and it is characterised by near neutral to slightly acid Na–Cl waters of comparatively high salinity and high P–CO 2 . Based on the different chemical signature of surface and ground waters (low-Cl type) from lake waters, mass balance methods have been applied to investigate lake dynamics. Water enters the lake mainly by precipitation and groundwater inflow, and leaves by groundwater outflow and evaporation. A large groundwater outflow of 2.4 m yr −1 has been estimated. The high salinity, Na–Cl signature of Lake Ngozi waters, together with 3 He/ 4 He ratios measured on dissolved gases (between 7 and 8.3 Ra) and high-P CO2 values estimated all along the water vertical column indicate the inflow of deep-seated fluids, likely magmatic in origin, into the lake. The existence of a hydrothermal system possibly at 250 °C in the root of the volcanic edifice is also hypothesised on the basis of solute geothermometry. Despite the current lack of vertical stratification, the lake is suspected to act as condenser for CO 2 and other gases of deep magmatic origin, and should be then further monitored for the risk of limnic eruptions as well as for environmental and climatic concerns. [ABSTRACT FROM AUTHOR]

We present a new well dated Holocene record of environmental change from Little Llangothlin Lagoon in eastern Australia derived from aquatic plant macrofossils, macroscopic charcoal flux, and sediment stratigraphy from multiple cores. Little Llangothlin was an ephemeral freshwater wetland exhibiting frequent dry phases between 9800 and 9300 calendar years before present (cal. yr BP). There was a switch to a more positive water balance after 9300 cal. yr BP, and by 8000 cal. yr BP, there was a lake that persisted until 6100 cal. yr BP. The period between 6100 and 1000 cal. yr BP was much drier, and there is no evidence for a permanent lake during this period. The Little Llangothlin record provides evidence for a wet phase during the Early to Middle Holocene (9000–6000 cal. yr BP) from the boundary region between temperate and tropical influences in eastern Australia. We propose that generally enhanced circulation after 9000 cal. yr BP explains the pattern of increasing moisture at the site at this time. The later Holocene climate at the site is consistent with other sites in south east Australia with a switch to generally drier conditions after 6000 cal. yr BP. [ABSTRACT FROM AUTHOR]