Emin C Dogrul

• PhD
• Senior Engineer at State of California

Finding a relationship between soil moisture and soil water flux at a single soil depth has been of particular interest in recent years. Such a relationship, however, is challenging to derive due to a high degree of nonlinearity of the soil water flow governing equation, known as Richards equation. This paper presents a new algebraic soil moisture-...

Groundwater is an important resource that meets part or all of the water demand in many developed basins. Since it is an integral part of the hydrologic cycle, management of groundwater resources must consider not only the management of surface flows but also the variability in climate. In addition, agricultural and urban activities both affect the...

The Integrated Water Flow Model (IWFM), developed by the California Department of Water Resources, is an integrated hydrological model that simulates key flow processes including groundwater flows, streamflow, stream–aquifer interactions, rainfall–runoff and infiltration. It also simulates the agricultural water demand as a function of soil, crop a...

Groundwater is an important resource. In many developed basins it meets part or all of the water demands. In addition, the management of groundwater resources directly impacts stream flows through stream-aquifer interactions. Yet many reservoir system analysis models that are used for the management of surface water resources either include a simpl...

As in many places, groundwater in California (USA) is the major alternative water source for agriculture during drought, so groundwater’s availability will drive some inevitable changes in the state’s water management. Currently, agricultural, environmental, and urban uses compete for groundwater, resulting in substantial overdraft in dry years wit...

This document describes utility programs developed to facilitate the calibration of IWFM models with PEST. The tools described in this report work with IWFM version 3.02. The utilities were developed to be general enough to be applicable to any IWFM model.

This paper describes an efficient methodology to link a comprehensive, distributed hydrologic model for California’s Central Valley to a crop production model. The resulting hydro-economic model allows for the dynamic calculation of crop acreages in response to water availability without simplifying groundwater or stream flow dynamics by the assump...

This report describes the input and output files for the California Central Valley Groundwater-Surface Water Simulation Model (C2VSim). C2VSim is an integrated numerical model simulating land surface processes and groundwater and surface water flows in the main alluvial aquifer system of California’s Central Valley (figure 1). C2VSim was developed...

Unstructured mesh generation has long been a labor-intensive and time-consuming aspect of hydrologic modeling. This is largely due to the iterative nature of the process and the limited integration between the specialized mesh generation software and Geographic Information Systems (GIS). To facilitate mesh generation for integrated hydrologic model...

We used the California Central Valley Groundwater-Surface Water Simulation Model (C2VSim), an integrated hydrologic model of the 50,000 km2 alluvial portion of California's Central Valley, to estimate the impacts of recent fluctuations in surface water diversions on Central Valley aquifers. C2VSim is an application of the Integrated Water Flow Mode...

An open problem that arises when using modern iterative linear solvers, such as the preconditioned conjugate gradient method or Generalized Minimum RESidual (GMRES) method, is how to choose the residual tolerance in the linear solver to be consistent with the tolerance on the solution error. This problem is especially acute for integrated groundwat...

An important issue that integrated hydrologic models (IHMs) for river basins can address is the management of water resources in heavily inhabited and cultivated basins. To address this issue, these models need to simulate water demands and root zone flows in a basin. Irrigation scheduling models (ISMs) have been widely used by professionals to com...

Field study is an essential component of hydrologic science because all hydrological studies must be conducted by such observation-based knowledge of real watersheds. Hillslope runoff processes have been intensively investigated, but the flow process at the boundary between the snowpack and ground surface has not been well documented. A field site...

Automated calibration of integrated hydrologic models, which simultaneously simulate several linked hydrologic processes, may provide more robust parameter estimates than automated calibration of models of a single hydrologic process owing to the direct linkage of multiple hydrologic processes within the integrated model. Simulated values of flows...

In this paper, we describe the accuracy control and performance en-hancement of linear solvers for the Integrated Water Flow Model (IWFM). This model is used by the State of California Department of Water Re-sources to assess the impact of climate change on water resources and the analysis of different conjunctive use scenarios across California. I...

In developed watersheds, the stresses on surface and subsurface water resources are generally created by groundwater pumping and stream flow diversions to satisfy agricultural and urban water requirements. The application of pumping and diversion to meet these requirements also affects the surface and subsurface water system through recharge of the...

Predicted global mean temperature increases will change the rates and timing of mountain-front discharges and thus the availability of surface water supplies for agricultural and urban water consumers. California's water supply and distribution system collects runoff from the Sierra Nevada Mountain range in the northeastern and eastern part of the...

In the popular Newton-Krylov methods for solving large-scale systems of nonlinear equations, inner linear systems resulting from outer Newton linearization are solved by Krylov iterative linear solvers. The accuracy control of Krylov solvers are based on the progress of the Newton iteration to achieve good local convergence while avoid-ing over-sol...

  A series of drought simulations were performed for the California Central Valley using computer applications developed by the California Department of Water Resources and historical datasets representing a range of droughts from mild to severe for time periods lasting up to 60 years. Land use, agricultural cropping patterns, and water demand were...

A series of drought simulations were performed for the California Central Valley using computer applications developed by the California Department of Water Resources and historical datasets representing droughts from mild to severe for periods lasting up to 60 years. Land use, cropping patterns, and water demand were fixed at 2003 levels and water...

Applications integrating land surface and root-zone processes with groundwater and surface water flow at the watershed scale (e.g. IWFM, SHE and the MODFLOW Farm Process) provide more robust and flexible models by internally calculating inter-process fluxes. The direct linkage of multiple processes within a single application facilitates model cali...

In most groundwater modeling studies, quantification of the flow rates at domain and subdomain boundaries is as important as the computation of the groundwater heads. The computation of these flow rates is not a trivial task when a finite-element method is chosen to solve the groundwater equation. Generally, it is believed that finite-element metho...

A newly developed watershed environmental hydrology (WEHY) model is presented as a state-of-the-art nonpoint source (NPS) model. The model consists of hydrologic and environmental modules, and describes environmentally relevant hydrologic processes based upon physically based governing equations to model the fate of pollutants such as sediment and...

The finite element application IWFM has been used to develop an integrated groundwater-surface water model for California's Central Valley, an area of ~50,000 km2, to simulate the evolution of the groundwater flow system and historical groundwater-surface water interactions on a monthly time step from October 1921 to September 2003. The Central Val...

The Integrated Water Flow Model (IWFM) is a comprehensive input-driven application for simulating groundwater flow, surface water flow and land-surface hydrologic processes, and interactions between these processes, developed by the California Department of Water Resources (DWR). IWFM couples a 3-D finite element groundwater flow process and 1-D la...

The Watershed Environmental Hydrology model presents a new approach to the modeling of hydrologic processes in order to account for the effect of heterogeneity within natural watersheds. Toward this purpose, the point location-scale conservation equations for various hydrologic processes were upscaled in order to obtain their ensemble averaged form...

The upscaled hydrologic conservation equations in the Watershed Environmental Hydrology (WEHY) model are capable of taking into account the effect of heterogeneity within natural watersheds. Model parameters that are capable of describing the heterogeneity of the flow domains also need to be estimated. The parameters of the WEHY model are related t...

An ensemble-averaged prediction equation system for transient subsurface stormflow on sloping impermeable beds in heterogeneous hillslopes is derived by means of the regular perturbation method. The covariance of hydraulic conductivity and flow depth, which emerges during the derivation of mean flow depth, causes a closure problem. To close the equ...

WEHY model takes a new approach to the modeling of hydrologic processes in order to account for the effect of heterogeneity within natural watersheds. Toward this purpose, the point -scale conservation equations for various hydrologic processes were upscaled in order to obtain their ensemble averaged forms at the scale of the computational grid are...

Thesis (M.S.)--University of California, Davis, 1996. Degree granted in Civil Engineering.