Salinity management in river basins : modelling and management of the salt-affected Jarreh Reservoir (Iran)

The sources and origin of salts in the basin of the two salt- affected Shapur and Dalaki rivers (Southern Iran) and the processes involved in salinization have been studied. The extent of water deterioration have been identified by examining spatial changes in the rivers water quality. Among salinity management measures pertaining to water quality, the engineering measures are investigated. It appears that the construction and management of the planned Jarreh Reservoir on the Shapur River is the most feasible one.The dynamic reservoir simulation model, - DYRESM (Imberger, et al., 1978, Version 6.4) is adapted to simulate the salinity/temperature distribution, long-term behaviour and response to various management policies in this reservoir. A simplified method to account for the effect of sediment particles on density of inflows and the inflowing processes in mild bed slope reservoirs is introduced. The method applies only to the steady motion of a turbidity current that is neither depositing nor eroding sediments. The vertical propagation of sediment has not been modelled. This applies to those substances (like dissolved salt) that are not reacting physically or (bio)chemically with suspended particles.Various management options to minimize the salinity build-up in the reservoir are examined. Among these, the diversion of the most saline part of the summer flows to a point downstream of the last irrigation intakes will result in a significant water quality improvement. At the end of a 5-year simulation, only a weak salinity gradient remains in the reservoir. Based on simulations, using 15 years of data, and the salt balance calculation, the long-term behaviour of the Jarreh Reservoir is studied, It is shown that the salinity in the reservoir is largely determined by annual variabilty in the river discharge.</TT

USCID fourth international conference

Presented at the Role of irrigation and drainage in a sustainable future: USCID fourth international conference on irrigation and drainage on October 3-6, 2007 in Sacramento, California.Includes bibliographical references.Application of different irrigation management practices plays a considerable role in water saving to achieve potential yields. On the other hand, network water distribution schedule is a governing factor in this regard. In current study conducted in Mahabad plain in North West of Iran, four different irrigation managements on sugarbeet cultivation including traditional farmer's management, Furrow Deepening, Reduced Discharge per Deepened Furrow, and Alternate Furrow Irrigation have been studied in real farmers' fields measuring 10.2 hectares. Participatory management approach has been used while working in farmers' fields. Soils textures are silty clayey. Results of studies indicate that water used has been reduced considerably while higher root and sugar yields are obtained due to better on-farm water management practices. Water Use Efficiency, in kg of yield per m3 of water used, increased considerably under alternate furrow irrigation management in comparison to what obtained under traditional management. Results show application of alternate furrow irrigation in sugarbeet cultivation not only resulted in lesser water use per hectare, but also it increased both root and sugar yields and, consequently, higher water use efficiency was obtained. Assessments have been made on irrigation schedule imposed by the irrigation network and its effects on actual water requirements. Results show that the delivery schedule practiced in the network in incapable of delivering the actual amount of water requirement for the dominant crop of the scheme. Suggestions are made to the network operator to improve overall network efficiency including revisions on water resources planning and allocation and/or improve network operation system

Parameter identification for the linear equation of groundwater flow

A mathematical model is presented for identification of the parameter (S/T) in a two-dimensional, linear equation describing groundwater flow through a heterogeneous, isotropic aquifer. This model does not require an iterative solution of the aquifer equation, which is an essential characteristic of many, current identification schemes. The shape of the surface representing the piezometric head is approximated from measured samples with a second-degree polynomial. Then first and second derivatives are calculated by differentiating this polynomial, which has been fitted to the experimental data with a least squares technique. Since derivatives of the piezometric surface are calculated directly from experimental data in relatively small regions, the identification problem reduces: to the simultaneous solution of linear, algebraic equations of small dimension. No initial or boundary conditions are necessary. The method has been verified by assuming a value for S and comparing the resulting distribution of T with values that have been found in previous investigations of the region. A sensitivity analysis has been done to find the sensitivity of the method to the error in measured piezometric head