REGIONAL SCALE SEDIMENT YIELD MODELING USING GIS AND REMOTE SENSING

GHULAM NABI

(2004-Ph.D-CEWRE-02)

ABSTRACT

A grid based Regional Scale Sediment Yield Model RSSYM was setup different catchments of Indus basin using coarse resolution grid data. When coarse grid data is used, the land slope decreases and sediment delivery is reduced. In this study the slope averaging effect was minimized by using the fractal analysis approach. The fractal constant (a) and fractal dimension (D) equations were correlated with the standard deviation on elevation by Zhang et al. (2000). These equations for fractal constant and fractal dimension were developed using Digital Elevation Model of 1 km2 resolution (DEM) for local topography. The slope was computed for 250 m and 50 m downscaling from 1 km2 grid. A comparison was made between fractal constant equation and fractal dimension to scale down the slope parameter. Both equations were incorporated in RSSYM. The model was applied to Phulra catchment. The results showed that fractal dimension equation gives better results as compared to fractal constant. So the fractal dimension equation was incorporated in RSSYM.

The RSSYM was applied on three catchments of Indus basin namely Soan, Gariala and Phulra. For Phulra catchment of Siran river the total observed sediment was 0.304 million tons whereas the simulated sediment was 0.291 million tons. The coefficient of efficiency (COE) was 0.85 and the coefficient of determination was 0.83 which shows that there is a good correlation between the observed and simulated values.

In Gariala catchment the observed sediment was 6.01 million tons whereas simulated sediment was 6.80 million tons. The coefficient of efficiency for Gariala catchment was 0.91 and the coefficient of determination observed and simulated hydrograph was 0.81. Similarly for the Soan catchment the observed sediment was 10.61 million tons and simulated sediment was 12.29 million tons. The coefficient of determination and coefficient of efficiency for this catchment was 0.95 and 0.98 respectively.

The snowmelt runoff model SRM was applied to Astor catchment to test the applicability of temperature index approach for Indus basin. The terrain is difficult to measure the hydrological and hydraulics data. Most of the data was available at the outlet of the catchments. The input data included daily temperature and precipitation, dividing the catchment in to different zone depending on the elevation difference. The elevation zones were generated from the DEM of the area. The snow depletion curves were made for the snow covered area derived from the satellite data analysis on monthly basis. The model output was discharge hydrograph. The COE was 0.91 which shows that there is a good correlation between the observed and simulated values. The statistical test showed that model performance was good. The results of SRM model encouraged to use temperature index approach for snowmelt runoff estimation in the Indus basin.

A snowmelt runoff model was developed using temperature index approach. The model was coupled with regional scale sediment yield model RSSYM. The coupled model was named as modified regional scale sediment yield model (MRSSYM). The MRSSYM model was applied to Astor and Gilgit catchments.  For the Astor catchment total observed sediment load was 3.98 million tons whereas the simulated sediment load was 4.34 million tons. The coefficient of the model was 0.89 whereas the coefficient of determination was 0.83. Similarly for Gilgit catchment the measured and simulated sediment loads were 4.50 and 4.48 million tons respectively. The coefficient of efficiency and coefficient of determinations were 0.95 and 0.88 respectively. From the results it can be concluded that MRSSYM can be applied with confidence to various catchments of Indus basin where runoff is due to snowfall and snow melting.

IMPROVING OPERATIONAL PERFORMANCE AND MANAGEMENT OF CANAL IRRIGATION SYSTEM USING HYDRAULIC MODELING

JAVAID AKHTAR TARIQ

(2005-PhD-CEWRE- 05)

ABSTRACT

 Water resources development and management acquired new dimensions in Pakistan. Recently, the Government of Pakistan has taken strategic initiatives and primarily focused on governance, decentralization and participation of the farmers by transforming the Provincial Irrigation Department (PID) to the Frontier Irrigation and Drainage Authority (FIDA). Management responsibilities are decentralized at canal command level to Area Water Boards (AWBs) and most of the existing functions at distributary level are performed by the farmer’s organizations (FOs). Recently six distributaries have been handed over to the farmer organizations under the irrigation management transfer (IMT) programme in Swat Canal Area Water Board (SCAWB). 

The study was conducted to analyse the operational performance using hydraulic simulation modeling.  To assess the impact of IMT on the performance of the irrigation system a database oriented irrigation management information system (IMIS) technique has been developed and utilized. The Simulation of Irrigation Canal (SIC) hydrodynamic model was used to analyse the improved operational scenarios for the irrigation systems operation at distributary level, to provide the system managers and farmers organizations to update the managerial control and plan operational activities through improved understanding of the system. Results of the study revealed that irrigation supplies are in excess of the crop water requirements. The relative water supply (RWS) index varies from 1.66 to 2.02 during summer, whereas in winter it varies from 2.22 to 2.55. The delivery performance ratio (DPR) during summer varies from 0.78 to 0.83 and in winter from 0.63 to 0.73. Irrigation supplies were reliable over the whole growing season. Due to modernization of the irrigation systems and enhanced water allowance, the annual cropping intensity and yield have increased significantly. There is a prominent increase in yield of maize (40 percent), sugarcane (55 percent) and wheat (43 percent) while the cropping intensity has increased by 25 percent.

The Irrigation service fee (ISF) collection analysis indicated that all the FOs performed well during the first year (2004-05) of IMT and recovered 60 percent of the assessed ISF; whereas during the 2005-06 and 2006-07, ISF collected was very low. From these results it is evident that chances of successful cost recovery do not seem to be high.

Operational and regulation aspects of the main system also play a pivotal role in overall irrigation water management aspects. The SIC model was used to evaluate the effectiveness of physical infrastructures of the Chowki Distributary. Open flume outlets along the distributary behave as hyper-proportional irrespective of their position. The head bifurcator outlets are behaving hyper-proportional, whereas middle ones as perfect proportional and tail end as sub-proportional. The trifurcator outlets are behaving as hyper-proportional. The major causes are construction inaccuracies in setting the crest level, which lead the outlets to draw more or less than the design discharge.

To improve the manual operation of the Chowki Distributary irrigation system, different operational strategies were investigated and quantified. From the results of this study, it is suggested to operate the distributary head regulator manually based on fixed frequency operation. It is recommended that from May to July, the distributary should be operated at 90-80 percent of design discharge, 90-75  percent of design discharge from August to October and 75-85 percent of design discharge from December to April to adjust the over delivery due to high water allowance.  Hydraulic committees at each of the distributary should be established to operate the distributary according to crop demand. Awareness among the farmers should be created regarding the farm irrigation application methods to avoid over-irrigation and wastage of water.

DEVELOPMENT OF AN OPTIMUM FRAMEWORK FOR LARGE DAMS IMPACT ON POVERTY ALLEVIATION IN ARID REGIONS THROUGH SUSTAINABLE DEVELOPMENT

ALI ASGHAR IRAJPOOR

(2004-Ph.D-CEWRE-01)

ABSTRACT

A set of indicators for sustainable development were identified to be employed in developing countries. The selected indicators provided a good understanding of social and engineering outputs of water resources projects. The study meticulously looks into the pre dam bio-physical and socio-economic conditions in one of the arid region of Iran under the area commanded by Minab dam.  This dam was constructed in Hormozgan province of Iran in 1983 and its irrigation system was completed in 1986 which was followed by progressive expansion of irrigated agriculture which almost doubled in year 2006.

Results of the study showed that there are significant positive impacts of irrigation network of the dam but they were not same as the targeted objectives envisaged in the feasibility report of the project for example literacy rate increased from 41 percent (pre-project) to 74 percent in 2006. Similarly significant improvements were observed in health care, sanitation, education, and other disciplines. On the other hand, only 50-60 percent of the planned objectives were met for some indicators whereas no significant achievements had been made in the others. It means that after construction of the dam and irrigation system, development didn’t match with the planned goals of the project.  Most of the deficiency in the performance of primary objectives have root in the managements, even after, many years of project completion. For optimization of project performance an institutional framework has been proposed suggested by introducing a new organization named as Sustainable Project Organization (SPO). This organization may overcome the deficiency through capacity building and training of social and engineering organizations in the project area in the direction of comprehensive poverty alleviation. This study argues the world-wide controversy against construction of dam in arid zones which is ill-founded and based on a few short term, mitigable negative impacts, ignoring many long term positive impacts leading to   alleviating of chronic poverty in arid regions.