Estimation of the Bay Proval Volumein Lake Baikal Using the QGIS and the SAGA GIS Geographic Information Systems

The research estimated the water surface area and volume of the fishing bay Proval in Lake Baikal by using the QGIS and SAGA geographic information systems. Such characteristics are used by ichthyologists to assess the reception capacity of the water area. Additionally, we considered the cases when the water level drops by 0.6 and 1.2 meters. The results may be used to predict population size of Baikal omul in low-water periods.

The Effect of Climate Changes on The Fluctuation of The Water Level of Al- Razzaza Lake, Iraq

One of the serious environmental challenges that Iraq faces is climate changes and impacts of changing weather patterns and extreme global weather events. This paper addresses changes in the temporal and spatial characteristics of water levels of Razzaza Lake and response to climatic changes using archived series of Multispectral satellite images Landsat. TM, ETM+ and OLI images acquired on 1990, 2000 and of 2016. In order to extract, mapping the water surface area of the Razzaza Lake, Multispectral spectral band rationing the Normalized Difference Water Index (NDWI) technique was adopted, and the climatic elements data for the period (1990-2016) were analyzed which provide significant information of surface water. The results show that Razzaza Lake has a particularly sharp change rate in the water level and there are significant fluctuations on lake level and water surface area over the time.

Performance Analysis of a Floating Photovoltaic System and Estimation of the Evaporation Losses Reduction

Our research aims to achieve dual-positive effects in the presented study by raising photovoltaic (PV) panels over the water surface. With this, target experiments were primarily conducted to evaluate the efficiency increments of the PV panel while reducing its operating temperature through passive convective cooling obtained by raising it over water. The following objective was to estimate the reduction in water evaporation due to the shading effect induced by the panel placed inside the same basin. The performance of two PV panels was analyzed, one used for tests, the other as a reference. The characteristic curves were determined under the local environmental conditions of Cagliari, Italy. The true temperature reduction and efficiency gain calculations of panel P1 due to water cooling was achieved via the measured temperatures and calculated efficiencies of panel P2 at environmental conditions. The water height inside the basin was constantly monitored and maintained at approximately 7.5 cm below panel P1, which covered about 17% of the total water surface area. The presence of water underneath P1 leads to its efficiency increment on average by 2.7% (absolute) and about 17.22% (relative). At the same time, temperature of panel P1 dropped by 2.7 °C on average. The comparative water evaporation study conducted with and without P1 inside the basin showed a 30% reduction in water evaporation.

Abundance and Diurnal Time Activity Budget of the Threatened Species White-Headed Ducks (Anatidae: Oxyura leucocephala) in an Unprotected Area, Boussedra Marsh, Northeast Algeria

The white-headed duck is a globally threatened species and its populations have become fragmented and undergone major decline in recent decades. Changes including long-term abundance (five times from 2005 to 2018) and diurnal activity budget (2010−2011 and 2017−2018) with respect to the effect of habitat features at Boussedra marsh (unprotected area) were compiled in order to fill some gaps in the status and trend of North African populations. The population size of the white-headed duck decreased over years from 2010 to 2018 by about 52.81%, and was positively associated with interior vegetation area, but not significantly with water surface area. Trends of population dynamics differed among seasons, and the number was higher in wintering than breeding season. Sleeping (44.93%, 23.74%) and feeding (59.09%, 27.43%) were the dominant diurnal activities at both the years of study, respectively. Boussedra marsh plays an important ecological role as a diurnal forging habitat and reproduction site for this threatened species and as a shelter for other waterfowl.

Rapid Loss of Dissolved CO2 From a Subtropical Steep Headwater Stream

High-gradient headwater streams are major participants in the carbon (C) cycle because of their capabilities of emitting a significant amount of carbon dioxide (CO2). Notwithstanding, their CO2 emissions have been largely overlooked in previous studies owing to their small water surface area and are sometimes strenuous to be measured because of their narrow channel widths and strong turbulence. This study examined the spatial and seasonal variabilities of CO2 dynamics of a subtropical steep headwater stream fed by groundwater. Our study found that the pH and dissolved oxygen exhibited a general increasing trend away from the source of the headwater whereas the partial pressure of carbon dioxide (pCO2) showed a downward trend. The stream water pCO2 in the upper reach was found to be higher than the ambient level by 19–114 times, with an average drop of >70% at just 9.2 m from the groundwater source, demonstrating the potentially large emission of CO2 into the atmosphere within this short distance. Additionally, the sampling works conducted further downstream revealed that the CO2 derived from groundwater could almost completely dissipate within approximately half a kilometer downstream of the source. The concentrations of dissolved organic carbon and pCO2 were also lower during the period with lower air temperatures in the headwater stream, indicating temperature-dependent metabolism and decomposition of organic matter in soil might modulate the C dynamics in the headwater stream, although the rapid gas exchange along the stream remained the determinative factor. Our findings reassert that headwater streams are an essential source of CO2 and disregarding them from the studies of greenhouse gas emissions of inland waters would underestimate their potency to influence the global C cycle.

Ecosystems in Books: Evaluating the Inspirational Service of the Weser River in Germany

Attempts at assessing the monetary value of cultural ecosystem services has proven challenging due to their non-material and non-market characteristics. Innovative methods are needed to fill this methodological gap. In this paper, a novel approach is developed for evaluating the inspirational service, one type of valuable cultural service, of a specific ecosystem embodied in published books. Taking the Weser River in Germany as an example, a breadth of evidence found in 19 books shows the strong inspiration of the river to people living around it who create plenty of literary and artistic works that represent different faces of the river, such as novels, poems, folklore and paintings. Based on the prices of these books and the estimated number of persons who have read these books, the total value of the inspirational service provided by the Weser River is calculated as 168,499 € from 1980 to 2019, leading to the annual value of 5,616.63 €/year and the unit value of 0.24 €/ha/year with the water surface area of 23,123 ha and the period of 30 years. The advantages and shortcomings of this approach are discussed, and suggestions for the improvement and further research are made.

Relationship between Water Surface Area of Qingtu Lake and Ecological Water Delivery: A Case Study in Northwest China

Qingtu Lake is located between Tengger Desert and Badain Jilin Desert, Gansu Province, Northwest China. It is the terminal lake of Shiyang River. In recent years, Qingtu lake has maintained a certain area of water surface and vegetation by artificial water conveyance. It is of great significance in preventing the convergence of the two deserts and restraining the trend of ecological deterioration of Shiyang River Basin. The relationship between the water surface area and the ecological water conveyance have not been thoroughly investigated. This study analyzed the spatial and temporal distribution of water surface area of Qingtu Lake and surrounding reeds by interpreting remote sensing data; the change of water surface area under the influence of meteorological factors and water conveyance by linear regression; the water conveyance to maintain current water surface area by water balance method, as well as the reasonable ecological water delivery in high flow year, normal flow year and low flow year by the means of analyzing the upstream inflow and water consumption in Minqin Basin. The results showed that there is a significant correlation between the water surface area of Qingtu Lake, evaporation and ecological water conveyance, and the minimum and maximum water surface areas generally appear before and after water delivery, indicating that the ecological water delivery and evaporation are the two main factors affecting the water surface area change of Qingtu Lake. The result calculated by linear regression indicated that the ecological water delivery volume to maintain current water surface area of Qingtu Lake is 3.146 × 107 m3/yr, while the value was 3.136 × 107 m3/yr calculated by water balance method. These two results are similar and can be verified with each other. Reasonable ecological water conveyance of Qingtu Lake in high flow year, normal flow year and low flow years were 4 × 107 m3/yr, 3.2 × 107 m3/yr and 2.3 × 107 m3/yr, respectively.

Using space observations to monitor reservoir operations in the Lancang River

<p>Being a part of the Water Tower of Asia, the Mekong River originates from the Tibetan Plateau and flows through China, Myanmar, Laos, Thailand, Cambodia, and Vietnam. Its upper portion, also called the Lancang River, has abundant hydropower potential, which has been largely exploited during the three recent decades. To date, there are 11 operational dams (10 of them have a volume larger than 100 MCM) on the mainstream of the Lancang, controlling about 40% of the annual flow at Chiang Saen (the most upstream station of the Lower Mekong). The amount of water withheld in these dams is a potential source of controversy between China and downstream countries because it affects both the timing and volume of available water. Assessing the real impacts of these dams is a challenging task owing to the chronic lack of data on reservoirs' storage and operating patterns. To overcome this challenge, we exploit satellite images and altimetry data. The analysis focuses on 10 reservoirs and is conducted in three steps. First, we estimate the relationship between water elevation and surface area (E-A curve) for each reservoir. For this purpose, we either use DEM data or water surface area data (derived from satellite images) paired with altimetry-derived water levels. Second, with the Elevation-Area-Storage curve converted from each E-A curve, we calculate storage variability over time by using satellite image-derived reservoir water surface area. The result is collated with storage variability derived from altimetry data. In the last part of our analysis, focusing on the period 2008-2020, we show how the total withheld storage changed over time, we determine the rule curve of each reservoir and elucidate the role of reservoir filling strategies.</p>