Master thesis

Fahad Ejaz (2015)
A decision support system for an integrated irrigation and groundwater management in the Punjab region of Pakistan. Master thesis, Technische Universität Dresden, September 2015

ABSTRACT

Water shortage is becoming an increasing global problem especially in arid and semi-arid regions. The water demand is exceeding the sustainable water resources supply capacity. Agriculture sector is the largest water consumer and is responsible for fulfilling the food requirements of the world. With the increase in population the demand of fresh water has also increased. On one side the climate change results in variation of surface water while, on the other side the groundwater resources are depleting due to their unaccounted use especially for agricultural purposes. Under such a challenging situation there is a need to regulate the water resources based on latest technology and to find a sustainable solution. With the advancement in information system (IS) field, decision support system (DSS) helps the decision makers in decision making and strategic planning. The main goal of this study is to develop a DSS that integrates existing crop models together with spatially distributed groundwater flow model.

The developed decision support system (DSS) contains two fundamental components database (or knowledge base) and model processes. Database (DB) contains all the raw and processed data. Process models consisting of computer codes are used to calculate the following: a) evapotranspiration depending on crop-coefficients of different crops b) effective precipitation c) spatially distributed groundwater recharge d) spatially distributed pumping rate from wells e) groundwater flow using groundwater model (r.gwflow). The effect of these processes on the groundwater resources by changing the relevant parameters can be evaluated and alternative courses of action can be made. The input raster maps for the simulation of groundwater flow are provided by the database and stores back the spatially distributed water levels on monthly basis produced by groundwater flow model (r.gwflow). The DSS has the capacity to analyse the groundwater response by implementing different cropping patterns and irrigation schemes.

Subsequently, the developed DSS is applied for a real world water management problem in the region of Punjab, Pakistan. Two irrigation sub-divisions named Sultanpur and Bhagat are selected for this purpose. The study area consists of agricultural fertile land containing various crops which grows in two different seasons, i.e. Kharif and Rabi. Due to insufficient artificial canal water supplies study area depends heavily on groundwater resources to fulfil crop water requirements. In this study the groundwater balance of the study area based on actual situation (cropping patterns) is analysed. More insight in to the model was gained by developing three scenarios for three different cropping patterns. The different parameters like a) irrigation water application efficiency in the fields b) increase in canal water supply c) percentage of recharge from fields, are used for controlling the system processes in order to evaluate the groundwater response. The application of DSS on the study area confirms the exploitation of local groundwater resources. Two months, i.e., May and June contains maximum groundwater abstraction exceeding 250 MCM. 70% of the total water requirements are fulfilled by groundwater abstraction. The model proves its ability to achieve each scenario goal for different crops combination. Evaluating the alternatives under different conditions says, by cultivating the combination of cotton, fodder (millet) crops in Kharif season and wheat, fodder (oats, barley) in Rabi season can better help in the sustainable use of local groundwater resources. The developed DSS fulfils the purpose and it can be further extended to support more complex situations.