Fayez Abdulla

Application of a macroscale hydrologic model to estimate the water balance of the Arkansas‐Red River Basin

An approach for estimation of the parameters of a macroscale land surface hydrology model is illustrated for the Global and Water Cycle Experiment (GEWEX) Continental Scale International Project (GCIP) large-scale area southwest (LSA-SW) which essentially comprises the Arkansas-Red River basin. The macroscale land surface hydrology model parameters were estimated for 44 catchments within LSA-SW with areas ranging from 180 to 7100 km2 using an automated search procedure. The catchment parameters were then linearly interpolated and overlaid on a one degree grid, which was used to represent the drainage network. The macroscale grid network model was run off-line at a daily time step, forced by gridded station precipitation and potential evapotranspiration. The model-generated long-term mean streamflows were compared with observations (corrected for management effects such as reservoir storage and diversions) and were found to agree to within one percent for the Arkansas River and about two percent for the Red River. For both rivers, the model underestimates the seasonal peak streamflow in late spring, and overestimates the late summer and early fall minimum. Model-derived evapotranspiration, spatially averaged over the entire Arkansas-Red basin, was compared to evapotranspiration derived from an atmospheric moisture budget of the Arkansas-Red River basin. On an average annual basis, for the period 1973–1986, the two agree to within one percent. The mean seasonal cycles for the two estimates agree quite closely from late winter to midsummer. However, the hydrologic model estimates less evapotranspiration in the fall, and more in midwinter, than the atmospheric budget.

Uncertainty and reliability analysis applied to slope stability

In this paper, reliability analysis of slope stability is presented using two methods of uncertainty first-order second-moment method (FOSM) and Monte Carlo simulation method (MCSM). The results of these methods are compared using four recognized methods of slope stability. These are Ordinary method of slices, simplified Bishops method, simplified Janbus method and Spencers method. Two illustrative examples are presented in this paper: one is homogenous slope and the other is non-homogeneous layered slope. The study shows that the reliability index (β) is independent of the seed random number generator and a sample size of 700 or greater is a good choice for MCSM. In the case of homogeneous slope a good agreement is observed between the calculated (β) using FOSM and MCSM for both the Ordinary and the Bishops method. However, slight difference in (β) is observed between the two uncertainty methods whether Janbus method or Spencers method is used. In the case of the layered slope good agreement is obtained between the two uncertainty methods for Ordinary, Bishop and Janbu methods. Similar to example 1, Spencers method shows also slight difference in (β) between FOSM and MCSM methods. Model uncertainty is addressed by evaluating the relative performance of the three slope stability methods i.e. Ordinary, Bishop and Janbu methods as compared to Spencers method.

Estimation of the ARNO model baseflow parameters using daily streamflow data

Abstract An approach is described for estimation of baseflow parameters of the ARNO model, using historical baseflow recession sequences extracted from daily streamflow records. This approach allows four of the model parameters to be estimated without rainfall data, and effectively facilitates partitioning of the parameter estimation procedure so that parsimonious search procedures can be used to estimate the remaining storm response parameters separately. Three methods of optimization are evaluated for estimation of four baseflow parameters. These methods are the downhill Simplex (S), Simulated Annealing combined with the Simplex method (SA) and Shuffled Complex Evolution (SCE). These estimation procedures are explored in conjunction with four objective functions: (1) ordinary least squares; (2) ordinary least squares with Box–Cox transformation; (3) ordinary least squares on prewhitened residuals; (4) ordinary least squares applied to prewhitened with Box–Cox transformation of residuals. The effects of changing the seed random generator for both SA and SCE methods are also explored, as are the effects of the bounds of the parameters. Although all schemes converge to the same values of the objective function, SCE method was found to be less sensitive to these issues than both the SA and the Simplex schemes. Parameter uncertainty and interactions are investigated through estimation of the variance–covariance matrix and confidence intervals. As expected the parameters were found to be correlated and the covariance matrix was found to be not diagonal. Furthermore, the linearized confidence interval theory failed for about one-fourth of the catchments while the maximum likelihood theory did not fail for any of the catchments.

Modeling of groundwater flow for Mujib aquifer, Jordan

Jordan is an arid country with very limited water resources. Groundwater is the main source for its water supply. Mujib aquifer is located in the central part of Jordan and is a major source of drinking water for Amman, Madaba and Karak cities. High abstraction rates from Mujib aquifer during the previous years lead to a major decline in water levels and deterioration in groundwater quality. Therefore, proper groundwater management of Mujib aquifer is necessary; and groundwater flow modeling is essential for proper management. For this purpose, Modflow was used to build a groundwater flow model to simulate the behavior of the flow system under different stresses. The model was calibrated for steady state condition by matching observed and simulated initial head counter lines. Drawdown data for the period 1985–1995 were used to calibrate the transient model by matching simulated drawdown with the observed one. Then, the transient model was validated by using drawdown data for the period 1996–2002. The results of the calibrated model showed that the horizontal hydraulic conductivity of the B2/A7 aquifer ranges between 0.001 and 40m/d. Calibrated specific yield ranges from 0.0001 to 0.15. The water balance for the steady state condition of Mujib aquifer indicated that the total annual direct recharge is 20.4 × 106m3, the total annual inflow is 13.0 × 106 m3, springs discharge is 15.3 × 106 m3, and total annual outflow is 18.7 × 106 m3. Different scenarios were considered to predict aquifer system response under different conditions. The results of the sensitivity analysis show that the model is highly sensitive to horizontal hydraulic conductivity and anisotropy and with lower level to the recharge rates. Also the model is sensitive to specific yield

Methane Emissions from Domestic Waste Management Facilities in Jordan—Applicability of IPCC Methodology

ABSTRACT In this paper, methane emissions from municipal wastewater treatment plants and municipal solid waste (MSW) landfills in Jordan for 1994 have been estimated using the methodology developed by the Intergovernmental Panel on Climate Change (IPCC). For this purpose, the 14 domestic wastewater treatment plants in the country were surveyed. Generation rates and characterization of MSW components as well as dumping and landfilling practices were surveyed in order to estimate 1994 CH4 emissions from these sites. Locally available waste statistics were used in cases where those of the IPCC guidelines were not representative of Jordans statistics. Methane emissions from domestic wastewater in Jordan were estimated at 4.66 gigagrams (Gg). Total 1994 CH4 emissions from MSW management facilities in Jordan are estimated at 371.76 Gg—351.12 Gg (94.45%) from sanitary landfills, 19.83 Gg (5.33%) from MSW open dumps, and 0.81 Gg (0.22%) from raw sewage-water dumping ponds. Uncertainties associated with these estimations are presented.

Application of a rainfall-runoff model to three catchments in Iraq

Abstract The capability of the Surface inFiltration Baseflow (SFB) conceptual rainfall-runoff model to simulate streamflow for three catchments selected from northern Iraq is investigated. These catchments differ in their climatic regimes and physical characteristics. Three versions of the model were tested: the original three-parameter model (SFB), the modified five-parameter model (SFB-5), and the modified six-parameter model (SFB-6). The available daily precipitation, potential evapotranspiration and runoff data were used in conjunction with a simulated annealing (SA) optimization technique to calibrate the various versions of the SFB model. A simple sensitivity analysis was then carried out to determine the relative importance of the model parameters. The study indicated that use of the original three parameter model was not adequate to simulate monthly streamflow in the selected catchments. The modified version (SFB-5) provided better runoff simulation than the original SFB model; overall a 19% increase was observed in the coefficient of determination (R2) between simulated and observed monthly runoff. The SFB-5 model performed with varying degrees of success among the catchments. The model performance in the validation stage was reasonable and comparable to that of the calibration stage. The sensitivity analysis of the SFB model for arid catchments revealed that the baseflow parameter (B) was the most sensitive one, while the S and F parameters were less sensitive than the B parameter.

Single Event Watershed Model for Simulating Runoff Hydrograph in Desert Regions

This study is aimed to use the available limited meteorologicaland hydrological data for two catchments located in the westernIraqi desert, to develop and apply a simple single event watershed model to simulate and predict the surface runoff hydrograph. The single event watershed model is based on the water balance equation. The inputs to the model are rainfall,evaporation, and soil properties data. The Resonbrock optimization technique is employed to determine the optimum parameters of the model. Also a simple and a modified versionof this model is suggested and tested for the study area. Theavailable rainfall and runoff data in these catchments have beenused in calibrating and testing the model. In model testing, theoptimized parameters for a particular storm are used to test themodel performance on other available storms and so on. Sensitivity analysis has been used to determine the most sensitive parameters.

A model for the determination of residential water demand by the use of tracers

A model that determines nodal demands by making tracer concentration measurements at specific nodes is developed. The model minimizes the difference between calculated and measured tracer concentrations to determine the unknown demands. Even-, over-, and under-determined cases are considered. For the purpose of verifying the model, tracer concentrations obtained by the model for known demands are considered as measurements. Results showed that the model made very accurate prediction of the unknown demands for both the even-, and the over-determined cases. The under-determined case made less accurate but still good estimates of the unknown demands for the scenarios considered here. The relationship between the sensitivity of the measurement location to the unknown demand and the accuracy of the determined demand is verified. Results showed that the model makes accurate estimation of the unknown demands if measurements are made at sensitive nodes while errors are introduced to the determined demand as a result of assuming measurements at nodes of low sensitivity.

Application of extreme value statistics to annual maximum magnitudes in Jordan employing a mixture distribution

The concept of extreme value mixture distribution (EV mix ) has been implemented in this study to estimate maximum earthquake magnitude occurrence. The EV mix model is applied to annual maximum earthquake magnitude occurrence in Jordan and conterminous regions spanning over the period 1918 to 1997. The maximum likelihood method, in conjunction with the two optimization methods, was employed for determining the statistical parameters of the Gumbels asymptotic distribution, i.e., GI, and the extreme value distributions EVIII and EV mix . The Simplex method of Nelder and Mead (1965) was found to be more successful in obtaining the maximum likelihood estimators of the three given distributions than the Newton-Raphson method. The difficulties inherent to the Newton-Raphson method were overcome by the Simplex method. It is shown in this study that the EV mix model fits the observed annual maxima far better than GI and EVIII models. In addition, the maximum likelihood estimators obtained using the Simplex method were used to calculate the earthquake risk for a given return period and a design lifetime of structures.

Evaluation of irrigation water total suspended solids (TSS) on a farm scale

Abstract This study tackled the problem of the irrigation water Total Suspended Solids (TSS) on a farm level in the northern Jordan Valley, Jordan. Two field experiments were conducted to evaluate the efficiency of the procedures applied for irrigation network flushing. The first experiment showed the effect of laterals flushing on sediments build-up and development. Good managed and regularly flushed block (Block A) compared to a block managed by the farmer (Block B) showed a reduction in the amount of sediments in the laterals and sediments build up started at emitter number 56 along the lateral in block A compared to emitter 26 in Block B. The second experiment confirmed the need of flushing on farm level. The results of this study showed that 95% of the emitters clogging took place in the last half of the laterals. Clogging of the water passage inside the emitter caused 65% of the clogging and 25% caused by the interior screen clogging. Flushing was carried out for all the pipes in the network in the selected farms, and its duration ranged between 5 and 10 min. Significant decreases in TSS were achieved that ranged from 20.9 – 99.9% in the two studied farms.