Rainfall and other forms of Precipitation

The report discusses the application of deterministic and stochastic approaches in daily rainfall-runoff modeling. The structure of a simple hydrologic water balance type conceptual model of daily time scale is discussed and tested on three catchments of India. Further, the deviations of historic and computed runoff series obtained by using the model, which indicate the error in the fitting of model, is analyzed and used to improve the predicted flows.

The report presents a seasonal rainfall-runoff model developed for the Saurashtra region as well as parts of Narmada river basin. The successful planning and implementation of water resources projects require reliable data on volumetric runoff. It is not feasible to have discharge stations in all the river basins of interest given resource constraints. Therefore, regional rainfall-runoff models are preferred. The utility of such models can be improved if rainfall-runoff models for different regions are developed using data specific to the regions.

The research study attempts to develop a rainfall-runoff model using the Artificial Neural Network (ANN) technique for the Baitarni river in Orissa. A detailed review of the research work in the area of interest revealed that the approach of neural computations was very effective in developing the required model, due to its various advantages. Accordingly, three candidate models based on ANN architecture were developed for the study area, to represent rainfall-runoff transformation.

In the study, raingauge network design has been developed for the Pagladiya basin of Brahmaputra river in Nalbari, Assam and Bhutan. Precipitation is the most basic data required for any water resources study and the estimation of the number & location of raingauge stations that provide adequate information regarding rainfall falling over the catchment is referred to as network design. A raingauge network is intended to serve general as well as specific purposes such as water supply, hydropower generation, flood forecasting, irrigation and flood control.

This report by ACWADAM describes the results of a research study conducted under the DFID funded AGRAR project at the Kolwan site in Pune district of Maharashtra state in India. The research focused on studying the usefulness of artificial recharge to augment groundwater resources through watershed development.

An important criterion of the study was also to understand the impact of artificial recharge on already changing livelihoods in areas where watershed development was conducted on a large scale.

The report attempts to do a comparison of single and multiple flow direction algorithms for computing topographic parameters in TOPMODEL. Topography is an important factor that influences the physical phenomenon of rainfall-runoff. Undeniably, it plays a primary role in the gravity drainage within a basin. In the last decade, ever-developing computer techniques associated with the greater availability of terrain data in digital form has favored the production of physically based models, which have spatial variability of topography built into their structure.

The report presents the seasonal mapping of water bodies along the Andhra coast using satellite data to analyze the pre-monsoon and post-monsoon variations in the reservoirs. Water resources development be it construction of reservoir, anicut or irrigation canal, calls for mapping of the various water bodies to throw light on its behavior in different seasons in order to plan a judicious water management scheme.

Remote sensing methods are considered to be more appropriate than conventional methods for collection of such information owing to their capability to provide broad synoptic and repetitive coverage of the area in a multi-spectral mode.

The study focuses attention on the use of inverse modeling technique for estimation of rainfall-recharge in a coastal aquifer. MODINV (Modular Inverse Model), which is software for parameter optimization of 3-D groundwater flow model, MODFLOW is applied to the Central Godavari delta in Andhra Pradesh to estimate the distributed rainfall-recharge during monsoon season.

This document by ACWADAM is a report of a rapid geohydrological assessment of some of the microwatersheds from parts of Bolangir district Orissa.

Bolangir district in Orissa forms a part of one of the hottest and backward regions of India with low land-productivity, and opportunities and technologies for agriculture in the district remain relatively unexplored.

Vagaries of rainfall and the underlying hard-rock geology further compound the problem and limit agricultural productivity to a great extent. Given such natural uncertainties, systematic implementation of a watershed management programme is the most viable avenue to overcome the problems of this region.

Bolangir district was thus selected as pilot area to conduct a pre-feasibility exercise for planning of water resources management. ACWADAM, Pune was invited, along with Samaj Pragati Sahayog, Bagli to conduct this pre-feasibility exercise.

In this study, regional flood frequency relationships have been developed using L-moments for South Bihar, in the alluvial plains of Indo-Gangetic basin and Kaimur-Chhotanagpur Santhal Pargana plateau. The annual maximum peak flood data of twenty-two gauging sites whose catchment areas vary from 11.7 to 3171 sqkm have been used. The mean annual peak floods of these sites vary from 29.15 cumec to 1293.2 cumec. Comparative regional flood frequency analysis studies have been carried out using some of the commonly used frequency distributions viz Extreme Value (EV1), General Extreme Value (GEV), Normal, Log Pareto (GPA) and Wakeby based on L-moments approach.