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The purpose of this paper is to compare trophic characteristics of the ecosystems of small and shallow lakes with a different character of land-cover in their catchments (as exemplified by several previously unstudied lakes of the Leningrad Region, North-Western Russia, that belong to a single lake-river system).

The key limnetic parameters of four lakes are analysed. Two of the lakes are located on the territory of allotment gardens, the other two are in the forest-covered areas. A preliminary assessment was made for the production-to-destruction ratio in the ecosystems of the lakes of the study region and their vulnerability factors.

For the lakes with a largely unexploited catchment, humus of terrigenous origin can act as a “hidden” source of nutrient load (primarily as phosphates). For the lakes with a catchment occupied by allotment gardens, an elevated trophic status and intensive overgrowth by vegetation (floating forms) is driven by an increased nitrogen load.

The results can be used for planning land and water management activities in North-Western Russia and in other world’s regions with similar environmental conditions.

These results can lay a foundation for creating a region-specific model to predict trends in eutrophication and overgrowth of small shallow lakes.

Songkhla Lake is the largest lake in Thailand along the Bay of Thailand, situated at latitude 7°08′ and 7°50′ north and longitude 100°07′ and 100°37′ east (Fig. 4.1). The lake covers an area of approximately 1,042km², and consists of four interconnected lake ecosystems (Ratanachai & Sutiwipakorn, 2005): Thale Noi (approximately 27km²), Thale Luang (approximately 473km²), Thale Sap (approximately 360km²), and Thale Sap Songkhla (approximately 182km²).

The hydrologic losses due to net evaporation in the Aral Sea have interesting analogs in the interior-drainage basins of the American West. Each of the three places discussed here – the Salton Sea, Owens Lake, and Mono Lake – has its own unique historical and geographic circumstances, but the story of each place has certain parallels to the Aral Sea disaster. Each place experienced dramatic water losses during much of the 20th century, but the emergence of environmental science and law in recent decades has caused significant policy changes. The Salton Sea is still declining, and modest efforts by state and federal agencies to halt the decline are inadequate. A proposal to build dikes to save part of the water body and convert the rest to salt evaporation ponds cited the Aral Sea as a model for the Salton Sea's future. The dry Owens Lake bed yields windblown dust that exceeds the Clean Air standard for fine particulate matter (PM 10), so Los Angeles is now required to release additional water back into the basin to create more shallow wetlands. In Mono Lake, a negotiated settlement has reversed the water loss while protecting vital interests of all parties, and a substantial ecological restoration plan is being implemented. The history of the American analogs to the Aral Sea, especially the success story of Mono Lake, may indicate potential pathways to progress in reducing problems caused by large-scale water diversion.

Recently, Colac Otway Shire in Australia released its management plan for Lake Colac, claiming over‐enrichment of the lake with nutrients and degraded water quality. This paper aims to investigate these claims by establishing a correlation between key water and ecological indicators and land uses.

The paper examines the correlation between impairment and stressors in Lake Colac. This was achieved by identifying the likely sources of pollutants into Lake Colac; identifying any existing monitoring program; and characterizing the water and sediment inputs. The likely impacts of increased nutrients and sediment levels on indigenous flora and fauna were also examined. The use of meiofauna (very small benthic metazoan animals) was investigated as an indicator of degraded sites. Plankton diversity as a measure of water health was also assessed.

Water quality in Lake Colac was found to vary both temporally and spatially, and exhibited low attainment against acceptable trigger values/objectives. At current levels the lake can be classified as poorly degraded. Likely sources of pollution were identified to be related to land uses in the catchments. The biota of the lake, investigated at four study sites, yielded a sparse, benthic macrofaunal assemblage that was dominated by oligochaetes. In contrast, an abundant and taxonomically diverse meiofaunal assemblage was noted. Future meiofaunal analyses are likely to resolve suitable biotic indicator species of free‐living nematodes in response to land use and waterway threats specified in the study.

This work will provide a better understanding of integrated environmental systems to enable development of best management practices, thus transforming the way the land and water are used in the future. Following the present work, other key water and ecological indicators (increased dispersion and dominance of biological species) at five additional sites were studied. Alternative management options for the effluent generated at Colac Sewage Treatment Plant and possible ecological effects of each option were also evaluated. More recently, a sediment characterization study was also carried out at sensitive sites representative of locations where build up of sediments and algae outbreaks are reported. This will enable classification of sediment and evaluation of dredging options.

Deepor Beel is one of the Ramsar Site and a wetland of great biodiversity, situated in the south-western part of Guwahati, Assam. With urban development at its forefront city of Guwahati, Deepor Beel is under constant threat. The study aims to calculate the lake water volume from the water surface area and the underwater terrain data using a triangulated irregular network (TIN) volume model.

The lake water surface boundaries for each year were combined with field-observed water level data to generate a description of the underwater terrain. Time series LANDSAT images of 2001, 2011 and 2019 were used to extract the modified normalized difference water index (MNDWI) in GIS domain.

The MNDWI was 0.462 in 2001 which reduced to 0.240 in 2019. This shows that the lake water storage capacity shrank in the last 2 decades. This leads to a major problem, i.e. the storage capacity of the lake has been declining gradually from 20.95 million m³ in 2001 to 16.73 million m³ in 2011 and further declined to 15.35 million m³ in 2019. The fast decline in lake water volume is a serious concern in the age of rapid urbanization of big cities like Guwahati.

None of the studies have been done previously to analyze the decline in the volume of Deepor Beel lake. Therefore, this study will provide useful insights in the water resource management and the conservation of Deepor Beel lake.