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Water quality of wetland ecosystems is a critical concern due to its implications on human health and aquatic life. This study was conducted to assess the spatial and temporal variation of water quality in Kotagala wetland to understand its impact on water safety for domestic uses and ecosystem health. Water samples were collected (n = 70) from six inlets and the wetland outlet from November 2021 to August 2022, and analyzed for pH, electrical conductivity (EC), salinity, total dissolved solids (TDS), total suspended solids (TSS), nitrate, and phosphate. The pH, EC, and nitrate showed significant correlations. Spatial clustering divided the monitoring sites into two clusters, as areas of higher and lower pollution levels. Discriminant analysis highlighted the significance of EC, pH, and nitrate concentrations in differentiating these clusters. Principal According to principal component analysis (PCA) 88.8% of the total variance of spatial variation in water quality was explained by the first two components. Temporal clustering following seasonal variations revealed the influence of rainfall pattern on water quality. EC, TDS, TSS, and nitrate concentrations emerged as the most important factors in this temporal categorization. In PCA, 76.8% of the total variance of temporal variation in water quality was explained by the first two components. Findings highlight the urgent need for sustainable strategies and policies to mitigate the impacts of human activities on wetland water quality, since water quality variations in the wetland was significantly impacted by direct human activities, and variations in rainfall trends in the area. [ABSTRACT FROM AUTHOR]

Analysis of historical data on rainfall and streamflow provides useful information for water resources management in a river basin. The objective of this study was to assess the variations and trend analysis of rainfall and streamflow data in the upper Maduru Oya sub watershed in Sri Lanka during a 30 year period (1989 October to 2019 September) using daily rainfall data from two gauging locations (Padiyathalawa and Bibile) and daily average streamflow data from one gauging location (Padiyathalawa). Descriptive statistics were used to assess the variations. The Mann Kendal Trend Test (MK test) and Innovative Trend Analysis method (ITA) were used to analyze the trend, and Sen's Slope Estimator was used to assess the magnitude of the trend. Based on the MK test, most of the rainfall trends obtained are in an increasing direction, and streamflow trends are in a decreasing direction. Rainfall trends found in Padiyathalawa are not statistically significant. Annual, First Inter Monsoon, March, and May time scales of rainfall showed significant upward trends at Bibile (p<0.1) while streamflow in January, April, and September showed significant negative trends (p<0.1) at Padiyathalawa. The results displayed by all three tests were in very good agreement for rainfall. ITA results showed similar trend types of 77%, 95% and 41% at Padiyathalawa and Bibile rainfall and streamflow, respectively. A significant positive (p<0.01) strong and lower correlation between the trend value of the ITA and the Z value of the MK test were found for rainfall and streamflow, respectively. Changes in rainfall are not sufficient to explain the observed trends in streamflow. Therefore, future research should be directed at the causal aspects of streamflow change in this watershed. [ABSTRACT FROM AUTHOR]

Frequently occurring extreme weather events have caused agricultural production losses in considerable amounts in the dry zone of Sri Lanka. Hence, it is important to understand the farmer groups and the systems that are highly vulnerable to climate change before proposing remedial measures. Paddy is the main crop cultivated by the dry zone farmers in Sri Lanka. The majority of the farmers cultivate paddy during the Maha season while Other Field Crops (OFC) are cultivated in the Yala season in the same land due to water scarcity. This study developed a climate vulnerability index for OFC farmers and tested the applicability of the developed vulnerability index using major and minor irrigation systems. For this study, secondary data was collected from relevant government institutions and field- level organizations. Yield data, demographic data, socioeconomic data, and marketing data were collected through a questionnaire survey. Indicators were selected under three dimensions of vulnerability, representing physical and environmental factors, socioeconomic factors, and external assistance factors. All indicators were calculated for each major and minor irrigation system separately. The results revealed that, farmers in both irrigation systems are highly vulnerable to the external assistance index while scoring low in the physical and environmental index and the socio-economic index. The minor irrigation scheme has a high external assistance to climate change compared to the major irrigation scheme. Overall vulnerability index results Indicated that, the climatic vulnerability of farmers in minor irrigation system is higher (61.6) than in major irrigation systems (57.1). Thus, these types of indices are useful in assessing the status of the farmers so that interventions can be applied to reduce their vulnerability and facilitate their livelihoods. [ABSTRACT FROM AUTHOR]

Agriculture in the dry zone of Sri Lanka is highly constrained by the inadequacy of irrigation water. The small village tanks located in these areas help farmers to cultivate their lands during dry periods by storing rainwater. However, the rainfall variability has made a considerable threat to functioning of these tanks and in providing expected benefits to the farmers. The objective of this study was to assess the climatic variability using 30-year (1989 to 2018) daily rainfall data from six rain gauging locations (Anuradhapura, Mahagalkadawala, Hingurakgoda, MahaIlluppallama, Girithale and Diyabeduma) in a small tank dominated area in the Dry Zone. Standard Precipitation Index (SPI) was calculated to assess the temporal variability of dry and wet extremes. Mann Kendal Trend Test (MK test) was used to analyze the trend of SPI and Sen's Slope Estimator to assess the magnitude of the trend. The results of Anuradhapura, Diyabeduma and Mahagalkadawala show significantly increasing trend of SPI 12/annual rainfall. According to the SPI, there were increasing trends in First Inter Monsoon in Anuradhapura and MahaIlluppallama, which have resulted an increasing rainfall trend in Yala season. Additionally, there was an increasing trend in Second Inter-Monsoon in Anuradhapura. These changes highlight that there are extreme rainfall events occurring in some seasons without making a significant impact in the annual rainfall pattern of the area. [ABSTRACT FROM AUTHOR]

The article presents a minimum information requirement model for simulation of flow and nutrient transport from agricultural systems. The study aims to determine the local flow and nutrient losses at the research scale for runoff events, and to understand larger scale catchments applications, where there is a need to reflect a distribution of land uses and hydrological regimes. It provides three case studies to reflect the range of applicability of the model. It shows how different runoff and nutrient loss regimes in different soil/geological and global locations can be simulated using the same model.