Page 201 - Biosystems Engineering

GIS-Based W atershed Modeling Systems 179

smaller than 1000 ha for best results. Runoff is calculated based on the
Hortonian approach using a modified version of the Smith–Parlange
(Smith and Parlange 1978) infiltration model. KINEROS-2 requires
the watershed to be divided into homogeneous overland flow planes
and channel segments and routs water movement over these ele-
ments in a cascading fashion. An implicit finite difference numerical
scheme in a one-dimensional framework is used for mass balance
and kinematic wave approximations to the Saint–Venant equations.
KINEROS-2 accounts for erosion resulting from raindrop energy and
by flowing water separately. A mass balance equation is solved to
describe sediment dynamics at any point along a surface flow path.
Erosion is based on maximum transport capacity determined by
Engelund–Hansen equation (1967). A first-order uptake rate is to
determine rate of sediment transfer between soil and water. KINE-
ROS-2 can be used under the Automated Geospatial Watershed
Assessment system (AGWA) (described later), which provides a GIS
interface for data preparation and visualization of results.

MIKE SHE
MIKE SHE, from the Danish Hydraulic Institute (DHI) is an inte-
grated hydrological modeling system for simulating surface and
groundwater flows. The user-friendly tools provided by MIKE SHE
can simulate the entire land phase of the hydrologic cycle and allows
components to be used independently and customized to local needs.
MIKE SHE emerged from the System Hydrologique European (SHE)
as developed and extensively applied since 1977 onward by a consor-
tium of three European organizations: the Institute of Hydrology (the
United Kingdom), Société Grenobloise d’Etudes et d’Application
Hydrauliques (SOGREAH) (France), and DHI Water.Environment.
Health (Denmark). Since then, DHI has continuously put forth efforts
in development and research on MIKE SHE. MIKE SHE can be used
for the analysis, planning, and management of a wide range of water
resources and environmental problems related to surface water and
groundwater. Examples include surface water impact from ground-
water withdrawal, conjunctive use of groundwater and surface water,
wetland management and restoration, river basin management and
planning, environmental impact assessments, aquifer vulnerability
mapping with dynamic recharge and surface water boundaries,
groundwater management, floodplain studies, impact studies for
changes in land use, climate, and agricultural practices.
MIKE SHE is a watershed model and is distributed parameter
and physically based. It is capable of handling both single events and
continuous simulations. The watershed is divided into square grid
cells. Overland flow routing is based on two-dimensional diffusive
wave equations, where options vary for channel flow from simple
Muskingum routing to the Higher Order Dynamic Wave formulation
of the Saint–Venant equations. Groundwater flow is solved with the