This research plan was made for Surabaya City study case area in order to know the impact of land use and land cover change.

1. Research Theme
The Impact of Land-Use in Lowland and Coastal Area on The Groundwater (A Case Study in
Surabaya City, East Java, Indonesia)
The Background of Study
Surabaya is the second largest urban city in Indonesia. It is located between 112,30
to 1130
E
longitude and 70
to 7,30
latitude in East Java, Indonesia in the south and west of Madura Strait.
Currently there are 31 district and 163 sub-district whitin Surabaya City. Surabaya as the center
of regional development in East Java Province, is the center of economic activities in East Java,
Bali and other eastern Indonesia regions, with the presence of Tanjung Perak Port as its main
trading and manufacturing activities. Surabaya can divided into two topographic areas : lowland
plain and rolling plain [1]. The lowland plain has and elevation of up to 5 m and prevailing slope
0-2% above low tide level in the southern, eastern and northen portion of the city. While rolling
plain which is located in the western portion of this city have 5 m elevation above low tide level
and the slope is 2-15%. In nothern part of Surabaya, damaged caused by flood is relatively
higher because dominate of built up areas.
Coastal lowlands belong to one of the most vulnerable regions to coastal hazards. These area are
continuously threatened with the risk of coastal erosion, saltwater intrusion, disturbance of the
natural drainage and flooding. The flooding, most of time is not produced by the sea but from the
land itself. Most frequently it is the heavy rainfall over the mainland which cannot sufficiently be
drained to the sea that causes the flood [2]. Because of the growing demands of the increasing
population, industries and tourism, excessive groundwater is pumped from the aquifiers in the
subsurface. The catasthropic consequence of excessive groundwater withdrawal in coastal area
will lead to land subsidence due to sediment compaction [3]. Therefore, well balanced
groundwater management has became important in coastal and lowland area.
The Purpose of The Study
The main purpose of this study is to observe the impact of urbanization on land-use changes on
the groundwater system in coastal and lowland area due to excessive groundwater withdrawal.
obserbve the magnitude of groundwater recharge and discharge and identifying the areas which
is most sensitive to land use-changes.
Literature Review
The applicability of a ground water model to a real situation depends on the accuracy of the input
data and the parameters. Determination of these requires considerable study, like collection of
hydrological data (rainfall,evapotranspiration, irrigation, drainage) and determination of the
model parameters. WetSpass stands for Water and Energy Transfer between Soil, Plants and
Atmosphere under quasi-Steady State [5]. It is a physically based model for the estimation of

2. long-term average spatial patterns of groundwater recharge, surface runoff and
evapotranspiration employing physical and empirical relationships.The water balance
components of vegetated, bare soil and imprevious surfaces in WetSpass are calculated as
follows :
𝐸𝑇𝑟𝑎𝑠𝑡𝑒𝑟 = 𝑎𝑣𝐸𝑇𝑣 + 𝑎𝑠𝐸𝑠 + 𝑎𝑜𝐸 𝑜 + 𝑎𝑖𝐸𝑖
𝑆𝑟𝑎𝑠𝑡𝑒𝑟 = 𝑎𝑣𝑆 𝑣 + 𝑎𝑠𝑆𝑠 + 𝑎𝑜𝑆 𝑜 + 𝑎𝑖𝑆𝑖
𝑅 𝑟𝑎𝑠𝑡𝑒𝑟 = 𝑎𝑣𝑅 𝑣 + 𝑎𝑠𝑅 𝑠 + 𝑎𝑜𝑅 𝑜 + 𝑎𝑖𝑅𝑖
Which are ETraster, Sraster, Rraster are the total evapotranspiration, surface runoff, and groundwater
recharge of a raster cell respectively, each having a vegetated, bare-soil, open-water and
impervious area component denoted by av, as, ao, and ai. Precipitation is taken as the starting
point for the computation of the water balance of each of the above mentioned components of a
raster cell, the rest of the processes (interception, runoff, evapotranspiration, and recharge)
follow in an orderly manner.
The water balance for a vegetated area depends on the average seasonal precipitation (P),
interception fraction (I), surface runoff (Sv), actual transpiration (Tv), and groundwater recharge
(Rv) all with the unit of [LT-1
], with the relation given below:
𝑃 = 𝐼 + 𝑆 𝑣 + 𝑇𝑣 + 𝑅 𝑣
Surface runoff (Sv) is calculated in relation to precipitation amount, precipitation intensity,
interception and soil infiltration capacity.
𝑆 𝑣 = 𝐶 𝐻𝑜𝑟 𝑆 𝑣−𝑝𝑜𝑡
Initially the potential surface runoff (Sv - pot) is calculated as :
𝑆 𝑣 − 𝑝𝑜𝑡 = 𝐶𝑠𝑣(𝑃 − 𝐼)
Which in Csv is a surface runoff coefficient for vegetated infiltration areas, and is a function of
vegetation, soil type and slope. Where CHor is a coefficient for parameterizing that forms part of a
seasonal precipitation contributing to the overland flow. CHor for groundwater discharge areas is
equal to 1.0 since all intensities of precipitation contribute to surface runoff.
The calculation of seasonal evatranspiration is obtained from open water evaporation and
vegetation coefficient
𝑇𝑟𝑣 = 𝑐𝐸 𝑜
Trv = the reference transpiration of a vegetated surface [LT-1
], Eo = potential evaporation of open
water [LT-1
] and c= vegetation coefficient [–].

3. This vegetation coefficient can be calculated as the ratio of reference vegetation transpiration as
given by the Penman-Monteith equation to the potential open-water evaporation, as given by the
Penman equation:
𝐶 =
1 +
𝛾
∆
1 +
𝛾
∆
(1 +
𝑟𝑐
𝑟𝑎
)
Which γ is psychrometric constant [ML
-1
T
-2
C
-1
], Δ is slope of the first derivative of the saturated
vapor pressure curve (slope of saturation vapor pressure at the prevailing air temperature)
[ML
1
T
-2
C
-1
], rc
= canopy resistance [TL
-1
] and ra
= aerodynamic resistance [TL
-1
] given by
𝑟𝑎 =
1
𝑘2 𝑢 𝑎
�𝑙𝑛 �
𝑧 𝑎 − 𝑑
𝑧0
��
2
Which k is the Von Karman constant (0.4) [–], ua
is the wind speed [LT
-1
] at measurement level
za
= 2m, d is the zero-plane displacement length [L] and zo
is the roughness length for the
vegetation or soil [L].For vegetated groundwater discharge areas, the actual transpiration (Tv) is
equal to the reference transpiration as there is no soil or water availability limitation
𝑇𝑣 = 𝑇𝑟𝑣 , 𝑖𝑓 (𝐺 𝑑 − ℎ 𝑡) ≤ 𝑅 𝑑
Which Gd
, is groundwater depth [L], ht
is the tension saturated height [L] and Rd
is the rooting
depth [L]. The last component, the groundwater recharge, is then calculated as a residual term of
the water balance can be calculated as follow :
𝑅 𝑣 = 𝑃 − 𝑆 𝑣 − 𝐸𝑇𝑣 − 𝐸𝑠 − 𝐼
ETvv
is the actual evapotranspiration [LT
-1
] given as the sum of transpiration Tv
and Es
(the
evaporation from bare soil found in between the vegetation). The spatially distributed recharge
is therefore estimated from the vegetation type, soil type, slope, groundwater depth, and climatic
variables of precipitation, potential evapotranspiration, temperature, and wind-speed. WetSpass
recharge outputs can be used as an input for the groundwater model like MODFLOW.
MODFLOW is an extremely versatile finite-difference groundwater model that simulates three-
dimensional groundwater flow through a porous medium [6].
𝑆𝑠 =
𝜕ℎ
𝜕𝑡
=
𝜕
𝜕𝑥
�𝐾𝑥𝑥
𝜕ℎ
𝜕𝑥
� +
𝜕
𝜕𝑦
�𝐾𝑥𝑥
𝜕ℎ
𝜕𝑦
� +
𝜕
𝜕𝑧
�𝐾𝑥𝑥
𝜕ℎ
𝜕𝑧
� − 𝑊
Ss is the specific storage of the porous material [L
-1
], Kxx, Kyy and Kzz are hydraulic
conductivity along the x, y and z coordinate axes, which are assumed to be parallel to the major
axes of hydraulic conductivity [LT
-1
], h is the potentiometric head [L] and W is volumetric flux
per unit volume, representing sources and/or sinks of water [L
3
T
-1
] and t is time [T]. The ground
water flow equation is solved using the finite-difference approximation.

4. Research Methodology
1. The variety of data is required for for groundwater management study in coastal and
lowland area. Therefore it is necessary to know what data is available, where and which
in format. The type of data required is related to [4] :
1. The geological structure of the subsoils
2. Water level in groundwater and surface water.
3. Source of groundwater pollution
4. The natural input of hydrological data (rainfall rate, astronomical range tide, etc)
The data requirement lists is prepared based on the available data and the data required
from this study. WetSpass requires a combination of ArcView grid file as input which are
listed : soil, topography, slope, land-use, temperature, precipitation, wind speed and
groundwater depth. While the common input files for MODFLOW will incule the
following : recharge, initial head, boundary mask, hydraulic and layer thickness, river or
drains and wells.
River network and main drainage system for Surabaya City will be compiled from
Surabaya Drainage Master Plan (SDMP) issued by Planning Berau of Surabaya City
[1].Existing lang use map and road network of Surabaya will be acquired from official
land use map issued by Planning Berau of Surabaya City
2. Describe the boundary conditions of the system which the groundwater flow takes place.
It include the presence of aquifiers, semi-permeable layers characterized by their
thickness and permeabilities.
3. The grondwater recharge is stimulated with the distributed Water and Energy Transfer
between Soil, Plants and Atmosphere underquasi-Steady State model (WetSpass) model
[5] which estimates spatially distributed runoff, evatransporation and recharge in function
of land cover, soil type and topography. The groundwater recharge is estimated from a
seasonal water balance.
R = P − S − ET − E − I
where R is groundwater recharge [LT−1
], P is the average seasonal precipitation [LT−1
], S
is runoff over land surface [LT−1
], ET is the actual evapotranspiration [LT−1
], E is
evaporation from the bare soil [LT−1
] and I is the interception by vegetation [LT−1
].
4. The groundwater system is modelled by applying the USGS modular three-dimensional
finite difference model (MODFLOW) [6] represent the groundwater recharge derrived
from WetSpass model. The inputs to the model consists of hydro-geological
characteristics of the lowland area,pumping wells, the regional distributed recharge
calculated previously, and the drainage levels. An initial estimate of the groundwater
depth is used along with the other WetSpass input grids (landuse type, soils, precipitation,
evapotranspiration, and wind-speed). The resulting spatially distributed groundwater

5. recharge output from the WetSpass run is then used as an input for MODFLOW for a
groundwater simulation. From this MODFLOW run a new groundwater depth will be
produced.
5. The result will be verified and analyse to know the impact of land-use changes on the
groundwater system.
Research Plan
This research is expected to be conducted at Graduate School of Department Civil Engineering,
Osaka University. Specification of study based on my main purpose will be finished by the first
year of study if the research is accepted. The other specific research in range of water
management in lowland and coastal area may conducted in the second year of my study.
References
[1] Susetyo, Cahyono. 2008. Urban Flood Management In Surabaya City : Anticipating Changes
in the Brantas River System.International Institute for Geo-information Science and Earth
Observation. MSc. Thesis [1]Baeteman, Cecile. 1999. Subsidence in Coastal Lowlands Due to
Groundwater Withdrawal : The Geological Approach. Journal of Coastal Research Special Issue.
Coastal Hazard (12).61-75
[2] J. Dams, S. T. Woldeamlak, and O. Batelaan. 2008. Predicting land-use change and its
impact on the groundwater system of the Kleine Nete catchment, Belgium. Hydrology and Earth
System Sciences (1). 1369-1385
[3] Mishira, Nitin., Khare, Deepak. 2014. Impact of Land Use Change on Groundwater- A
Review. Advances in Water Resource and Protection (AWRP). Vol.2. 28-41
[4] Batelaan, O. and De Smedt, F.2007 GIS-based recharge estimation by coupling surface-
subsurface water balances, J. Hydrol, 337(3–4), 337–35
[5]Rwanga, Sophia S. 2013. A Review on Groundwater Recharge Estimation Using Wetspass
Model. International Conference on Civil and Enviromental Engineering. 156-160
[6] Harbaugh, A. W. and McDonald, M. G. 2000.MODFLOW-2000, TheU.S. Geological Survey
modular groundwater model. User guideto modularization concepts and the groundwater flow
process,U.S. Geological Survey, Reston, Virginia, USA, Open File Rep. 00–92, 121