Regional streamflow network analysis using the generalized least square method: A case study in the Kizilirmak river basin

Hydrologic information is used to estimate the parameters of regional models so that they can be transferred to other sites where information is needed. In this study, an analysis is performed to obtain the best representative model with the available parameters to minimize the model error variance. The number of runoff stations, their locations, and the length of records are used to determine the sampling error variance for each station. The prediction error variances are determined with different station numbers by considering the length of records and cross correlation values

Estimation of seasonal runoff using remote sensing satellite data

Snow hydrology has been a relatively less investigated part of the hydrologic cycle. In the last two decades there has been a growing interest and scientific research to study the role of melting snow fbr the estimation of runoff mainly contributing to the storage in large reservoirs and to make the procedure operational on a real time basis. The paper describes a project related to satellite snow cover mapping and snowmelt runoff computations, which is currently carried out in eastern Turkey

Using MODIS snow cover maps in modeling snowmelt runoff process in the eastern part of Turkey

Water perhaps is the most valuable natural asset in the Middle East as it was a historical key for settlement and survival in Mesopotamia, "the land between two rivers". At present, the Euphrates and Tigris are the two largest trans-boundary rivers in Western Asia where Turkey, Syria, Iran, Iraq and Saudi Arabia are the riparian countries. The Euphrates and Tigris basins are largely fed from snow precipitation whereby nearly two-thirds occur in winter and may remain in the form of snow for half of the year. The concentration of discharge mainly from snowmelt during spring and early summer months causes not only extensive flooding, inundating large areas, but also the loss of much needed water required for irrigation and power generation purposes during the summer season. Accordingly, modeling of snow-covered area in the mountainous regions of Eastern Turkey, as being one of the major headwaters of Euphrates-Tigris basin, has significant importance in order to forecast snowmelt discharge especially for energy production, flood control, irrigation and reservoir operation optimization

Point-scale energy and mass balance snowpack simulations in the upper Karasu basin, Turkey

Since snowmelt runoff is important in the mountainous parts of the world, substantial efforts have been made to develop snowmelt models with many different levels of complexity to simulate the processes at the ground (soil-vegetation), within the snow, and at the interface with the atmosphere. Snow modifies the exchange of energy between the land surface and atmosphere and significantly affects the distribution of heating in the atmosphere by changing the surface albedo and regulating turbulent heat and momentum fluxes at the surface. Thus, for computing the amount of melt, the only strictly correct way is using an energy budget. A two-layer point model (SNOBAL) was applied to calculate the energy and mass balance of snowmelt in the upper Karasu basin, in eastern Turkey, during the 2002-04 snow seasons. The data on snow and climate were provided from automated snow and meteorological stations installed and upgraded to collect high-quality time series data of snow and meteorological variables, such as snow water equivalent, snow depth, precipitation and radiation, with automated data transfer. A number of analyses of snowpack energy and mass balance were carried out to understand the key processes that have major impacts on the snow simulation. Each form of energy transfer was evaluated during snow accumulation and ablation periods using a 2 h computational time step. The model results are appraised with respect both to temporal distribution (the model application for three consecutive snow seasons at one site) and to areal evaluation (the model application to three different sites for one season). The model performance is evaluated by comparing the results with observed snow water equivalent, snow depth and lysimeter yield. Copyright (c) 2006 John Wiley & Sons, Ltd

Groundwater recharge estimation from ephemeral streams. Case study: Wadi Tabalah, Saudi Arabia

Estimation of groundwater recharge to an unconfined aquifer is studied using analytical and numerical techniques and results are compared with field observations. There is an acute need for such estimation in water balance studies in arid climates, and the case study in this paper is for such a region. The wetting front movement in the unsaturated zone depends on antecedent soil moisture, the ponded water depth and its duration, and on the position of the water table and the hydraulic properties of the unsaturated zone. A hydraulic connection between the recharge basin and the aquifer is not immediately established because the wetting front is unsaturated

Simulation of event-based snowmelt runoff hydrographs based on snow depletion curves and the degree-day method

In mountainous regions, runoff from snowmelt is an important hydrologic and economic factor, and therefore early runoff forecasting brings significant advantages to the planning and operation of water resources systems. Similarly, predicting runoff from snowmelt during spring months in the eastern part of Turkey, where most of the water originates from high mountains and contributes to the large dams on the Euphrates River, is of crucial importance. In this study, an event-type, physically based hydrologic model Hydrologic Engineering Center (HEC-1) interfaced within the program Watershed Modeling System is applied to the Upper Karasu Basin to simulate rainfall-snowmelt hydrographs during 3 years. The model relates snowmelt to temperature using the degree-day factor, a common practice in the simulation of snowmelt. The model accounts for growth and depletion of the snowpack in terms of snow water equivalent, which is tracked in each of the elevation zones into which the basin is divided. The ground-truth data for snow are coupled with the snow depletion curves obtained from satellite data (NOAA-AVHRR) to determine snow water equivalent values at the beginning of each event