Live Storage Capacity Research Articles

Assessment of Siltation Impact and Mitigation Strategies for Sustaining Storage Capacity in Lwanyo Dam, Tanzania

The ongoing generation, transportation, and deposition of silt in the Lwanyo Dam has significantly reduced the storage capacity of the Lwanyo Reservoir, originally constructed to support irrigation and the surrounding ecosystem. The objective of this paper was to assess the extent of siltation in Lwanyo Dam, evaluate its impact on the dam's storage capacity, and propose measures to mitigate silt accumulation. The upstream catchment area, approximately 39.6 km², includes around 128,991 m² allocated for rain-fed crop cultivation and 5.89 km² for pastoral activities. Frequent overtopping of the reservoir has been observed, largely due to siltation reducing its live storage capacity. In the reservoir trial pits were excavated and assessed, and they indicate that average silt layers range in thickness from 0.54 m to 0.98 m per rainy season. The deposited material consists of a silt layer from 0 to 540 mm, followed by an intermediate clay layer from 540 mm to 3100 mm. The impounded silt depth was measured at 1270 mm, with an estimated siltation volume of 58,349.4644 m³. The reservoir's original storage capacity of 210,153 m³ has been reduced by 27.765% due to siltation. The reservoir’s structural design inadequately addresses silt management, lacking both silt flushing tunnels and upstream silt check dams. The analysis indicates that storage capacity decreases by 3.085% annually, and if this linear trend continues without any intervention measures, the dam will lose all storage capacity within 24 years. The study recommends urgent measures to mitigate silt accumulation.

Sedimentation Analysis of Ujani Dam

Abstract -The sedimentation is an effect of erosion on the catchment area of the reservoir and therefore, lesser the rate of erosion, smaller is the sediment load coming into the reservoir. Deposition of sedimentation in the reservoir moderately reduces the capacity of the reservoir. Both Dead storage capacity & live storage capacity gets affected due to sedimentation. Information about reduction in the storage capacity is important for the planning and operational purposes and the same can be obtained by sediment assessment surveys done at regular intervals. Various factors affect the process of erosion, transport and deposition of sediment in the reservoir. Type of soil, drainage density, vegetation, rainfall intensity and duration, shape of catchment and land use / land cover affect erosion. Sediment transportation totally depends upon slope of the catchment, channel geometry and nature of river bank and bed. Deposition is a function of bed slope of the reservoir, length of reservoir, flow patterns, inflow-outflow rates, grain size distribution, mode of reservoir operation etc Key Words: Ujani Dam, Sedimentation, Remote sensing

Assessment of Reservoir Sedimentation Using Geospatial Tools: A Case Study of Kadana Reservoir

Sediment deposition affects the storage capacity of the reservoirs. Periodic assessment of the storage capacity is needed for the efficient management of the reservoir. Conventional hydrographic survey methods are helpful in assessing the sediment deposition in the reservoir but costlier and time consuming. Integration of advanced remote sensing and geospatial technologies into reservoir sedimentation studies enhance data-driven decision-making, monitoring efficiency, and helps in sustainable reservoir operations under changing environmental conditions. This study was conducted to assess the sedimentation in the Kadana reservoir using the satellite data and water level records for the period 2000 to 2020 using QGIS & google earth engine (GEE). The results showed the loss of live storage due to sedimentation was 38.52% since impoundment and the loss in the live storage capacity was 22.79% after year 2000. GIS technique helps in reservoir management for the sustainable development of the reservoir by understanding the change in water storage capacity of the reservoirs and reservoir sedimentation.

Reservoir Sedimentation Assessment Using Geospatial Technology: A case Study of Dukan Reservoir, Sulaimani Governorate, Kurdistan Region, Iraq

The accumulation of sediment in reservoirs poses a major challenge that impacts the storage capacity, quality of water, and efficiency of hydroelectric power generation systems. Geospatial methods, including Geographic Information Systems (GIS) and Remote Sensing (RS), were used to assess Dukan Reservoir sediment quantities. Satellite and reservoir water level data from 2010 to 2022 were used for sedimentation assessment. The satellite data was used to analyze the water spread area, employing the Normalized Difference Water Index (NDWI) and Modified Normalized Difference Water Index (MNDWI) to enhance the water surface in the satellite imagery of Dukan Reservoir. The cone formula was employed to calculate the live storage capacity of the reservoir within two elevations. According to the study results, the live storage capacity of Dukan Reservoir at elevation 511.78 m had decreased from 8000 MCM to 7007.77MCM and 6923.53 MCM using NDWI and MNDWI respectively, due to sedimentation, resulting in a capacity loss of 14.59% and 15.83% for NDWI and MNDWI respectively. The annual sedimentation was 13.78 MCM and 14.95 MCM for NDWI and MNDWI, respectively. Joglekar's equation and Khosla's formula have demonstrated that the sedimentation rate in the Dukan reservoir exceeds the critical rate. The findings of this study will inform the development of sediment management strategies aimed at preserving the reservoir's capacity.

Reservoir capacity loss and sedimentation assessment of Dholbaha dam located in Punjab, India using remote sensing and bathymetric survey techniques

Abstract A study was undertaken to assess the live storage capacity of the Dholbaha reservoir located in Punjab, India using remote sensing and bathymetric survey techniques. The primary objectives included comparing the estimated capacity with findings from a bathymetric survey, refining the elevation-area-capacity curve, and determining the rate of capacity loss due to sediments deposition. This analysis utilized water elevation data spanning from 1987 to 2022 and satellite imageries from Landsat 7, 8 & 9. The satellite data was processed using software tools such as Erdas Imagine and ArcGIS. The water extent of the reservoir was calculated using Modified Normalized Difference Water Index (MNDWI). Over the course of 34 years, the reservoir experienced reductions in its dead, active, and total storage capacities by 81.5%, 19.7%, and 28.9%, respectively. These changes correspond to annual depletion rates of 2.40%, 0.58%, and 0.85%, respectively. The sediment yield from the surrounding catchment area was determined to be approximately 1203.56 m3/km2/year. The findings demonstrate substantial declines in Dholbaha reservoir storage capacities over a 34-year period (1987-2022) attributable to sedimentation. This underscores the critical need for sustainable water management and provides key insights for monitoring and strategic planning. The study advocates immediate, targeted interventions within the catchment area to mitigate sedimentation in the Dholbaha reservoir, highlighting the importance of ongoing sedimentation rate monitoring and collaboration with stakeholders for informed reservoir management and sustainable solutions to maintain water capacity for the region.

Valuation and Pricing of Surface Water Supplies in Pakistan

Pakistan has the largest contiguous, well-articulated, and comprehensive irrigation system in the world, with 3 storage reservoirs, 68 small dams, 19 diversion barrages, and 45 canal commands with 12 Link Canals for inter-basin transfer of water. About 0.1 million outlets supply water to the farmers to irrigate land besides more than 600,000 tubewells. The whole irrigation network commands an area of 45 million acres (18.22 Mha) out of which 79 percent is irrigated by canals or tubewells/wells. More than half of the canal irrigated areas (58 percent) is irrigated perennially and 42 percent nonperennially [NWSR (2002)]. The average annual flow of Indus River System is approximately 151.58 million acre feet (MAF) of which presently 103.81 MAF (128.1 BCM) is being diverted to irrigate farm lands [NWSR (2002)]. The present live storage capacity of the reservoirs is about 12.5 MAF (13 percent of river flows) compared with the original capacity of 15.7 MAF. The hydropower generation is constrained by seasonal inflows to reservoirs and irrigation requirements by Indus River System Authority. The generation dictated by irrigation requirements is the highest in the months of July to October. Little more than half of the diverted flows (55 percent) become available at farm gate, 42 percent infiltrate to groundwater reservoir and balance 3 percent is lost as evaporation. Of the total water that seeps down to the groundwater reservoir, including some 27 percent of farm gate supply through field seepage, nearly 85 percent is being extracted. Groundwater owing its existence to operational canal system, supplies over 40 percent of crop water requirements of the country

Cascade Reservoirs: An Exploration of Spatial Runoff Storage Sites for Water Harvesting and Mitigation of Climate Change Impacts, Using an Integrated Approach of GIS and Hydrological Modeling

Torrents play an essential role in water resources through rainfall in arid to semi-arid mountainous regions, serving large populations worldwide, and are also crucial in maintaining the downstream environment. The natural flows (floods, ephemeral flows) in arid hill regions result in potential hydrological fluctuations caused by climate change. However, the feasibility of eventual storage in remote hilly catchments would force a more sudden change. The current study was conducted in the lower part of the Khirthar National Range in the Sindh province of Pakistan, with the aim to explore spatial runoff storage sites for sustainable development to mitigate the impacts of climate change in arid areas. In total, 83 years of precipitation data were used to estimate water availability, along with satellite imagery for LULC pre- and post-monsoon conditions, delineation of watersheds, and identification of potential runoff storage locations and return periods, using Remote Sensing (RS)/Geographical Information System (GIS) 10.5.1, HEC-HMS 3.1, and Origin Pro 9.0 for statistical approaches. The model delineated two potential watersheds: Goth Sumar, covering an area of 61.0456 km2, wherein ten cascading reservoirs were identified, and Goth Baro, covering an area of 14,236 km2, wherein two cascading reservoirs were identified. Different storage capacities were determined for the cascade-type reservoirs. The maximum live volumetric potential storage of the reservoirs varies from 0.25 to 1.32 million cubic meters (MCM) in the villages of Baro and Sumar. The return periods have been estimated at 5, 10, 20, 25, 50, and 75 years, corresponding to 12.35, 16.47, 21.43, 21.72, 25.21, and 40.53 MCM for Goth Sumar, while Goth Baro’s storage capacity has been estimated at 2.88, 3.84, 5.00, 5.06, 5.88, and 9.45 MCM, respectively. All results obtained were authenticated using accuracy assessment, validation, and sensitivity analysis. The proposed potential storage sites were recommended for a planning period of five years. The live storage capacity of the identified cascade reservoirs can be improved by raising the marginal banks and developing the spillways to control inlet and outlet flow in order to maintain internal pressure on the reservoir banks. The stored water can be used for climate-friendly agricultural activities to increase crop production and productivity. The proposed study area has extensive experience with flood irrigation systems and rainwater harvesting to sustain agriculture due to rainfall being the only water resource (WR) in the region. However, the study area has enormous potential for surface runoff WRs, especially during the rainy season (monsoon); the current 2022 monsoon is showing flooding. The modeling approaches of Remote Sensing, GIS, and HEC-HMS play an important role in delineating watershed areas, developing hydrographs, and simulating water availability for different return periods by minimizing cost and time.

Erosion Risk Assessment for Prioritization of Conservation Measures in the Watershed of Genale Dawa-3 Hydropower Dam, Ethiopia

Sedimentation is a leading global problem that affects the environment and dams by reducing the live storage capacity of reservoirs and the life expectance of dams. Hence, prioritizing watersheds according to the risk of soil loss is crucial for extending the useful life of dams and reservoirs. The objectives of this study were to assess sediment flow in the Genale Dawa-3 reservoir, identify subbasins that are prone to soil erosion, and evaluate the impact of different management practices on minimizing sediment yields by using the Soil and Water Assessment Tool (SWAT) model. The SWAT model was calibrated and validated by observed streamflow and sediment data based on the SUFI-2 algorithm by SWAT-CUP, and its performance was assessed. The model simulated the average annual sediment yield; the input to the reservoir was 16.83 ton/ha/yr for the period of 1990–2015. From a total of 31 subbasins, 12 were categorized from high to very severe (11–60 ton/ha/yr) sediment-yielding subbasins and selected for sediment management. The simulated scenarios showed that the average annual sediment reductions at critical erosion hot spots in subbasins after the application of filter strips, soil/stone bund, terracing, and contour farming were 35.03%, 66.54%, 80.88%, and 53.11%, respectively. Therefore, this study concluded that reducing sediment yield by implementing terracing in critical areas at risk of soil erosion was more effective than other soil conservation measures. Overall, this research can help planners and decision-makers to implement appropriate soil conservation measures in the most erosive subwatersheds in order to extend the useful life of the Genale Dawa-3 hydropower dam and reservoir.

Footprints of Sedimentation on Loss of Reservoir Life using Satellite Remote Sensing Technique

Reservoir is the most important water storage systems especially in areas where groundwater potential is low which can be used for domestic, irrigation as well as industrial water supply. The sedimentation which is a natural phenomenon of settling sediment particles in a reservoir is observed to be enhanced with construction of dams due to change in flow dynamics. Sedimentation in a reservoir takes place in dead storage zone as well as in live storage zone causing reduction in useful capacity of reservoir over a period of time, thereby affecting the designed water supply planning. Sedimentation in live storage zone can be estimated using Remote Sensing Technique which will gives us synoptic view of a reservoir. Present study aimed at estimating a reduction in live storage capacity with the help of satellite imageries. For this, the Totladoh Reservoir which is situated on the boundary of Maharashtra and Madhya Pradesh, India has been selected for the study. Totladoh reservoir is situated in calc gneisses type of metamorphic rocks. Green and near-infrared bands were used to calculate the Normalized Difference Water Index (NDWI). The rate of siltation for Totladoh reservoir has been estimated for the period of 1982-2020 using LANDSAT 8 satellite imageries having 30 m spatial resolution. Percentage loss of live storage for year 2020 is found to be 17.63. Rate of Siltation in the reservoir is 1173 m3/km2/year which is more under prevailing conditions when compared to CWC values.

Numerical modelling of reservoir sedimentation for sustainable storage capacity – a geospatial approach

ABSTRACT Surface water change is a very important indicator for environmental, climatic, and anthropogenic activities. The sediment brought by the stream into the reservoir starts settling down and gets deposited on the bed of the reservoir at all levels. The finer particles are carried in suspension and settle down on the reservoir floor while some of these are passed over the spillway towards the downstream of a dam. If the concentration is high, density current occurs along the floor of the reservoir. The purpose of this study is to assess the sedimentation of the Poondi Reservoir using Satellite Remote-Sensing (SRS). This helps in providing full utilization capacity of reservoir by providing more storage and supply of fresh water to the catchment area. The sedimentation assessment was carried out using satellite data and reservoir water level data from 2000 to 2020. Water spread area was analyzed from satellite data. The NDWI has been used to delineate open water features and to enhance the presence of water surface and linear interpolation/extrapolation technique has been applied for water spread area at different elevation. Further, these areas were used to compute live storage capacity of reservoir between two elevations by Prismoidal formula.

Giluyskaya Hydropower – new approach to project development

Multivariate water-power calculations were carried out and the main parameters of the reservoired Gilyuyskaya HPP were justified. The Gilyuy river is located in the Amur Region of the Far Eastern Federal District and is a right tributary of the Zeya River. The mouth of the Gilyuy river is located above the power site of Zeyskaya HPP. Based on the water-power calculations, it was found that the most efficient way is to use live storage capacity of 3.13 km3 and the turbine flow rate of HPP equal to 268 m3/s. The installed power capacity of Giluyskaya HPP is justified on the basis of maximizing the net present value and is assumed to be 213 MW. Hydropower has three hydraulic units with radial-axial turbine RO115with impeller diameter of 3.35 m and synchronous speed of 214.3rpm.The high-head water power development includes as follows: a concrete gravity dam, a concrete spillway dam with nappe-shaped profile, a concrete power dam with three water inlets and three steel pipelines with a diameter of 4 m, as well as HPP building. The HPP building is 48.68 m long and consists of three hydropower units with a width of 16.23 m. The length of the tent of HPP building along the flowstream is 18.5 m. The assembly area is 24.34 m long.

Sedimentation analysis for a reservoir using remote sensing and GIS techniques

ABSTRACT Water storage structures raised on the rivers are subjected to sedimentation. The sedimentation is caused by deposition of eroded sediment particles carried by the streams just behind a dam in a reservoir. In this study, we carried out loss in live storage capacity of Samrat Ashok Sagar Reservoir, Vidisha, Madhya Pradesh, India due to sedimentation using satellite imageries with various combinations of color bands (green, red, blue, near infrared, etc.) and on the basis of degree of reflectance and absorption of particular wavelengths of light. Normalized difference water index (NDWI) derived through the combination of green and NIR bands images have been used to calculate the water spread at various elevations by creating false color composites (FCC). Seven dates of IRS-(R2/P6) L-3 satellite images covering live storage of reservoir in elevation as per the field records collected from the reservoir site have been analyzed using ArcGIS. The resulted sedimentation in the live storage of the reservoir is approximately 46.48 Mm3 for the span of 20 years (1997–2017). The rate of sedimentation in Samrat Ashok Sagar Reservoir is 2.324 Mm3/ year or 0.9% per year. Reservoir silting rate has also been compared with empirical formulas of Khosla’s and Joglekar’s.

Water balance analysis in perennial river flow: case study Pulau Laut, South Kalimantan

Water scarcity in dry land region is main problem which need to be solved as long the agricultural activity existed. The common technical way to sustain water is capturing rainfall and runoff and stored locally before they go through to the sea. Channel reservoir is simple water infrastructure or dam which consists of reinforced wall constructed by crossed a river channel to store run off flow and facilitate aquifer recharge. This paper aims to calculate a water balance to quantify the amount of water between the dam and hydrological system. Estimation of water balance is generated from rainfall data by Mock, Penman, and linked by mass conservation method. Volume of water during the dry season was gained consistently by 1964.53 m3 where it was above the minimum operation and the live storage capacity of this reservoir about 2,531 m3 where it was adequate to cover water demand for irrigation purpose. In conclusion, channel reservoir can utilize intermittent river channel to store water and be treated as isolated water storage structures with simple manufacture.

ROLE OF SAR DATA IN WATER BODY MAPPING AND RESERVOIR SEDIMENTATION ASSESSMENT

Abstract. Reservoir sedimentation is the major problem, due to it every year the reservoir capacity is lost to considerable amount. Surveying for assessment of the reservoir by conventional approach is time and money consuming. Geospatial technology provides ample opportunity in this field through the availability of high resolution satellite data from sensors such as Sentinel, Indian Remote Sensing Satellite, Landsat, and SPOT have been used to calculate the water spread area of the reservoir. However, due to presence of cloud in most of the optical data during onset of monsoon, the water spread at the lowest reservoir level could not be mapped. In turn the revised capacity or sedimentation is generally assessed between either below full reservoir level (FRL) or above maximum draw down level (MDDL). Nowadays, the microwave synthetic aperture radar (SAR) data at reasonable spatial resolution is available freely in public domain. Moreover, microwave data has capability to penetrate cloud and the information below cloud can easily be retrieved. To overcome the issues related to optical data, in the present study, the reservoir sedimentation for Ghataprabha reservoir was estimated using SAR data. Sentinel-1A data was used to delineate the water spread area for the water year of 2016–17. The original live storage capacity (1974) was estimated to be 1434.14 Mm3 at FRL 662.940 m by the authorities using the hydrographic survey during the commissioning of the reservoir in the year 1974. The live storage capacity was found out to be 1366.14 Mm3 at FRL, however, as per original elevation-area-capacity curve the live capacity is around 1262.404 Mm3 at 660.50 m. Estimated live storage capacity from Remote sensing approach (2016–17) was assesses as 1182.5 Mm3 at 660.51 m. The storage capacity has reduced from 1262.40 Mm3 (1974) to 1182.51 Mm3 i.e. around 171.732 Mm3. As per present analysis the rate of sedimentation is around 4 Mm3/yr. It was realized that using the SAR microwave data, the revised capacity of the reservoir from its near MDDL to FRL could be assessed through remote sensing approach.

Reservoir Sedimentation Assessment Through Remote Sensing and Hydrological Modelling

Reservoir sedimentation is the gradual accumulation of incoming sediments from upstream catchment leading to the reduction in useful storage capacity of the reservoir. Quantifying the reservoir sedimentation rate is essential for better water resources management. Conventional techniques such as hydrographic survey have limitations including time-consuming, cumbersome and costly. On the contrary, the availability of high resolution (both spatial and temporal) in public domain overcomes all these constraints. This study assessed Jayakwadi reservoir sedimentation using Landsat 8 OLI satellite data combined with ancillary data. Multi-date remotely sensed data were used to produce the water spread area of the reservoir, which was applied to compute the sedimentation rate. The revised live storage capacity of the reservoir between maximum and minimum levels observed under the period of analysis (2015–2017) was assessed utilizing the trapezoidal formula. The revised live storage capacity is assessed as 1942.258 against the designed capacity of 2170.935 Mm3 at full reservoir level. The total loss of reservoir capacity due to the sediment deposition during the period of 41 years (1975–2017) was estimated as 228.677 Mm3 (10.53%) which provided the average sedimentation rate of 5.58 Mm3 year1. As this technique also provides the capacity of the reservoir at the different elevation on the date of the satellite pass, the revised elevation–capacity curve was also developed. The sedimentation analysis usually provides the volume of sediment deposited and rate of the deposition. However, the interest of the reservoir authorities and water resources planner’s lies in sub-watershed-wise sediment yield, and the critical sub-watersheds upstream reservoir requires conservation, etc. Therefore, in the present study, Soil and Water Assessment Tool (SWAT) was used for the estimation of sediment yield of the reservoir. The average annual sediment yield obtained from the SWAT model using 36 years of data (1979–2014) was 13.144 Mm3 year−1 with the density of the soil (loamy and clay) of 1.44 ton m−3. The findings revealed that the rate of sedimentation obtained from the remote sensing-based methods is in agreement with the results of the hydrographic survey.

Evaluation of Capacity of Salandi Reservoir Using Remote Sensing Data Along With Qgis Software

The dynamic aspects of the reservoir which are water spread, suspended sediment distribution and concentration requires regular and periodical mapping and monitoring. Sedimentation in a reservoir affects the capacity of the reservoir by affecting both life and dead storages. The life of a reservoir depends on the rate of siltation. The various aspects and behavior of the reservoir sedimentation, like the process of sedimentation in the reservoir, sources of sediments, measures to check the sediment and limitations of space technology have been discussed in this report. Multi satellite remote sensing data provide information on elevation contours in the form of water spread area. Any reduction in reservoir water spread area at a specified elevation corresponding to the date of satellite data is an indication of sediment deposition. Thus the quality of sediment load that is settled down over a period of time can be determined by evaluating the change in the aerial spread of the reservoir at various elevations. Salandi reservoir project work was completed in 1982 and the same is taken as the year of first impounding. The original gross and live storages capacities were 565 MCM& 556.50 MCM respectively. In SRS CWC (2009), they found that live storage capacity of the Salandi reservoir is 518.61 MCM witnessing a loss of 37.89 MCM (i.e. 6.81%) in a period of 27 years.The data obtained through satellite enables us to study the aspects on various scales and at different stages. This report comprises of the use of satellite to obtain data for the years 2009-2013 through remote sensing in the sedimentation study of Salandi reservoir. After analysis of the satellite data in the present study(2017), it is found that live capacity of the reservoir of the Salandi reservoir in 2017 is 524.19MCM witnessing a loss of 32.31 MCM (i.e. 5.80%)in a period of 35 years. This accounts for live capacity loss of 0.16 % per annum since 1982. The trap efficiencies of this reservoir evaluated by using Brown’s, Brune’s and Gill’s methods are 94.03%, 98.01and 99.94% respectively. Thus, the average trap efficiency of the Salandi Reservoir is obtained as 97.32%.

Assessment of sedimentation in Pong and Bhakra reservoirs in Himachal Pradesh, India, using geospatial technique

All water storage structures constructed on natural rivers are subjected to reservoir sedimentation. The reservoir sedimentation is filling of the reservoir behind a dam with sediment carried into the reservoir by streams. The sediment particles which originate from erosion processes in the catchment are propagated along with the river flow. When the flow of a river is stored in a reservoir, the sediment settled down in the reservoir and reduces its capacity. Decrease in the storage capacity of a reservoir beyond a limit hampers the purpose for which it was constructed. Therefore, assessment of sediment deposition becomes very important for the management and operation of such reservoirs. Some conventional methods, such as hydrographic survey and inflow-outflow approaches, are being used to estimate the sediment deposition in a reservoir, but these methods are tedious, time-consuming and costly. Consequently, in this study, a remote sensing data based digital image processing technique was used to assess the sedimentation in Pong and Bhakra reservoirs, located in foothill of Western Himalayas, India. Seven dates of IRS-(P6) LISS-III satellite data from maximum to minimum reservoir level were used to assess temporal and spatial patterns of reservoirs. The water spread areas of the reservoirs were assessed by using a band rationing technique i.e. Normalized Difference Water Index (NDWI). Furthermore, the revised capacities of the reservoirs between minimum and maximum levels were computed using the trapezoidal formula. From the analysis, it has been observed that the live storage capacity of Pong Reservoir, due to sedimentation, was estimated as 632.84Mm3 in last 35 years (1974–2009), whereas it was determined as 802.34Mm3 for Bhakra reservoir in the span of 46 years (1963–2009). Further, the sedimentation rate in the Pong reservoir was calculated as 18.08Mm3/year, while for the Bhakra reservoir it was 17.46Mm3/year. These sedimentation rates are comparable with the hydrographic survey analysis.

HYDROLOGICAL STUDY AND ANALYSIS FOR PROPOSED SARTIK DAM PART 2: RESERVOIR CHARACTERISTICS, SIMULATION MODEL, AND FLOOD ROUTING CALCULATIONS

This research is the part 2 of hydrological study and analysis for proposed Sartik dam which located on the Lesser Zab River, the second largest tributary of Tigris River at 18 km northeast of Altun Kopri town, within Erbil governorate of Iraqi Kurdistan Region. In this part water demand from the dam is calculated, the dam power generating facility with an installed capacity amounting to 156 MW with a maximum discharge of 300 m3/sec. The characteristics of the dam reservoir were calculated, from reservoir sedimentation calculation the dead storage level and capacity was determined and was equal to (309 m.a.s.l., and 104,304,031 m3) respectively. The monthly and annual water losses due to evaporation were calculated from daily recorded evaporation using an equation based on area, volume and elevation curve, and the annual losses were equal to (51,132.366 m3), also the normal reservoir water level (NWL) was fixed at 325 m.a.s.l. which gives live storage capacity equal to (384,846,885), and flooded area equal to (34.184 km2). The simulation model of the dam reservoir, prepared from the calculation of water inflow into the reservoir and water demand including evaporation losses. The inflow was taken for different types of water years, dry (deficit) years (1984, and 1999), average water years (1981, and 1995) inflow, and maximum (flood) water years (1969 and 1988) inflow. From the curves, it is clear that the reservoir starts full at month April and ends full at month March during one year taking into account that the maximum water storage in the reservoir is (489,150,916)m3 and minimum storage is (104,304,031) m3. The flood routing study was done using the (PMF, 1000, 100, 50, and 25) years return periods inflow hydrographs, and stage and volume curve by fixing the crest level of ogee spillway will at 320 m.a.s.l., choosing the number of gated spans equal to 7, the length of each span equal to 12m, and the initial water level of the reservoir was 325 m.a.s.l. The results of this routing will be used to determine the design parameters of the spillway and to determine the actual need of the emergency spillway.

Assessment of reservoir sedimentation using remote sensing and recommendations for desilting Patratu Reservoir, India

ABSTRACTThis study describes the assessment of reservoir sedimentation of the Patratu Reservoir using Satellite Remote Sensing (SRS). The sedimentation assessment was carried out using satellite data and reservoir water level data from 2006 to 2012. Water spread area was analysed from satellite data. The Normalized Difference Water Index (NDWI) has been used to delineate open water features and to enhance the presence of water surface in satellite imagery of the Patratu Reservoir. Water spread area of the reservoir at a particular elevation on the date of the passing of the satellite was used to develop an elevation-area curve. For the present case, fluctuation of water level was found to vary from 387.096 to 406.152 m. The linear interpolation/extrapolation technique has been employed to assess the water spread area of Patratu Reservoir at different elevations. Further, these areas were used to compute the live storage capacity of the reservoir between two elevations by the Prismoidal formula. From the study, it was found that due to sedimentation, the live storage capacity of Patratu Reservoir has reduced from 101.95 to 89.96 hm3, thus showing capacity loss of 11.76% in a span of 44 years. To increase the live storage capacity of the reservoir it is proposed to adopt manual and mechanical digging combined with flushing for desilting of the deposited sediment.EDITOR D. Koutsoyiannis ASSOCIATE EDITOR S. Kanae

Capacity assessment of the Qattara Depression: Egypt as a sink for the global sea level rise

One of the most prominent geomorphological features in the Western Desert of Egypt is the occurrence of the Qattara Depression (20,800 km2 or 2% of Egypt’s area), which has the deepest point in Africa. Topographic analysis of the depression was carried out using fine resolution digital elevation models acquired from the Advanced Spaceborne Thermal Emission and Reflection Radiometer-Global Digital Elevation Model (ASTER-GDEM) in order to assess the capacity of the depression. Results showed that the lower point in the depression occurs at −136 m and its capacity at the sea level is 1340 billion m3, which equals 10 times the live storage capacity of the Lake Nasser behind the Aswan High Dam. Although the depression has the aptitude to be a reservoir for any augmentation in the sea level, detailed environmental impact assessment studies should be implemented to address geologic, climatic, biologic as well as socio-economic impacts.