Rivers

The report describes the software, which has been developed for flood control regulation of a system of reservoirs. The reservoirs can be gated or ungated, and the system can have any combination including weirs and diversions. For operation of reservoirs, the scenario has been divided into two categories depending on the reservoir level and inflows - normal operation and emergency operation.

The input data requirements of the software are modest. This software along with previously developed software for conservation operation would provide a complete set of tools to analyze any system configuration for the range of purposes for which reservoirs are commonly built in India.

The report uses the Soil Conservation Services (SCS, 1956), Curve Number (SCS-CN) method, a widely used event based rainfall-runoff method for simulating daily rainfall-runoff data of three catchments, viz., Ramganga and Hemavathi catchments of the sub-humid regions and Sabarmati catchment of the arid region of India.

In the model formulation, the daily variation of parameter, potential maximum retention is governed by the known antecedent moisture condition. Hydrologic simulation studies provide a useful and important input to water resources planning and watershed management practices.

The report discusses the water availability computations under different data availability scenarios. Water availability generally refers to the volume of water available from the basin or stream at a particular point over a specified period of time. Volumetric relationship is reflected between rainfall and runoff. Many factors like climatic and basin characteristics affect the water availability of a basin. Time and space distribution of rainfall, its intensity and duration, surface vegetation, soil moisture, soil characteristics, topography and drainage network are some of the important factors.

The study attempts to apply Geomorphological Instantaneous Unit Hydrograph (GIUH) and Geographical Information Systems (GIS) based approach for flood estimation. The design storm data of four catchments along with morphological characteristics have been considered. The geomorphological parameters and time area diagrams for each of the dam catchments were generated using the GIS package, Integrated Land and Water Information Systems (ILWIS).

The geomorphological parameters together with the time-area diagram forms an important input for the GIUH based Clark model. This model has been applied for deriving the instantaneous unit hydrograph and thereby to estimate the design flood in four dam catchments located in Luni and Chambal basins in Rajasthan viz. Jawai, Sei, Gamabhiri and Alnia. A review of the previous studies carried out using GIUH approach has been presented. Furthermore, a review of studies carried out using GIS techniques is also provided.

The hydrological inventory of Ganga basin provides information regarding availability of hydrological data and highlights major hydrological problems of the basins. The information is a useful input in water resources planning, management and research activities.

The study estimates the average contribution of snow and glacier melt runoff in the annual flow of Satluj river at Bhakra dam. This study is restricted to the Indian part of Satluj basin. A water balance approach was used to determine the average snow and glacier contribution to the annual flows.

The study deals with flood estimation through computation of a flood hydrograph for the ungauged Narmada catchment upto Jamtara using the physical and geo-morphological characteristics of the catchment. The catchment area of 17100 sqkm has been sub-divided into five sub-catchments for the purpose of flood estimation.

The study attempts to do field and laboratory determination of soil classification properties in the Dudhnai river basin of Assam and Meghalaya. Point infiltration tests using double ring infiltrometer were conducted at various locations (forty-four sites) in respect of different land use conditions. Soil samples were collected from these infiltration testing sites.

The saturated hydraulic conductivity was determined in the field using Guelph Permeameter for the selected sites. The undisturbed soil samples and disturbed soil samples (50 cm below the ground) were collected and subjected to elaborate laboratory tests. 

The study was taken up as a part of the representative basin studies being done by NIH and involved hydrological land use & land cover mapping for the Suddagedda basin of Andhra Pradesh. Mapping was carried out through visual interpretation for the years December 1987, April 1989, December 1992 and November 1996 using IRS IB-LISS II, LANDSAT 5-TM and IRS IC-LISS III data.

Land use and land cover are the most important surface characteristics of a basin. They are very dynamic features over space and time and it is difficult to get real time information on them through conventional means. Planners need to update knowledge of natural resources, which can be obtained quickly, economically and accurately through remote sensing techniques. Further, the land use map of a basin or region provides hydrologically significant categories, which are essential for estimation of reliable runoff from ungauged basins.

The study attempts to find out the effects of geomorphology on watershed runoff response in the Devak basin and tries to identify the parameters that are more closely related to runoff. A chief objective of the study is to regionalize the hydrologic models describing the rainfall-runoff process. 

The advanced knowledge of geomorphology of the region is of importance in the field of flood control measures and engineering projects, since geomorphological characteristics of river basins in mountainous areas affect runoff processes and formation of floods in the areas.