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ASSESSING THE IMPACT OF LANDUSE/LAND COVER CHANGE ON STREAM FLOW AND FUTURE PREDICTIONS OF LANDUSE/LAND COVER CHANGES OF BELES SUB-BASIN, UPPER BLUE NILE BASIN, ETHIOPIA
(Hawassa University, 2023-08-22) TSEGA MOGES
Landuse and land cover change drives changes that limit availability of products and
services for human, and it can undermine environmental health. Studying impact of
landuse/land cover changes on the stream flow is very important for proper basin
management. Hence this study investigated the past and potential future land cover changes,
and the impact of the past on the stream flow of Beles Sub-Basin using using the Soil Water
Assessment Tool (SWAT). To analyze the change that in the study area, satellite images were
downloaded for 1987, 2002, and 2019 years and processed using ERDAS Imagine 2014.
Then using supervised image classification, the satellite images were classified to
agriculture, wetland, forest, shrub land, and urban land. Accuracy assessment was done,
and overall accuracy of 86.25%, 88.7% and 87.9%, were achieved for the classified images
of 1987, 2002 and 2019 respectively. The net changes of landuse/land cover of the study
area from 1987 to 2019 indicated that forest, shrub land and wet land decreased by 4.73%,
10.59%, and 1.10%, respectively, while Agriculture, and Urban, increased by 14.18%, and
2.24%, respectively. The future LULCs of 2035 and 2055 were projected by IDRISI (CA Markov method), and the result indicated an increase of Agriculture 10.94%, Urban
44.04%, where as forest -12.63%, shrub land -11.35%, and wetland -43.61% decreased. Ten
parameters identified to be sensitive for the stream flow. Model calibration was carried out
using observed stream flow data from (1989-2010) and The validation was performed from
(2011-2019). Both results showed good match between measured and simulated stream flow
data with R
2 and ENS achieved 0.80, 0.74 for calibration and 0.64, 0.78 for validation
respectively. Due to LULCC, the mean annual Stream flow increased by 3.04m3
/s from
1987-2002, and, 2.83m3
/s from 2002-2019 and seasonal flow increased by 12.05m
3
/s, and
5.49m
3
/s in the wet season, while increased and decreased by 2.13m
3
/s and -2.78m
3
/s
respectively in the dry season. The surface runoff increased, while groundwater flow
decreased from 1987 to 2002 and from the year 2002 to 2019 the mean monthly stream flow
increased by 23.29m3
/s for the wet months while for the dry months decreased by 6.31m3
/s.
The Stream flow change to different predefined study years indicates LULCC has significant
impacts on the stream flow of the study area. To mitigate LULCC, local and national officials
in the Beles Sub-Basin should be invited to develop and implement scientific and suitable
planning and management plans
THE WATER SUPPLY AND DEMAND ANALYSIS IN THE CASE OF BONOSHA TOWN SHASHOGO WOREDA HADIYA ZONE SNNPR
(Hawassa University, 2021-12-24) TIMOTIWOS TUFA
The main objectives of this study was to analyze water supply and demand of Bonosha town
water distribution system. The supply part was assessed by collecting data of water source
yield in town, which is located north of the town. The town has single water source, which
has 4 l/s yield. To evaluate the demand of the town population, number of schools, churches,
mosques, health institution, government office and restaurants are assessed. To analyze the
existing water distribution system, the EPANET model was developed.The model used to
identify the level of velocity through pipe and the zone of high and low pressure. The result
of research shows that the non-domestic and domestic water supply coverage of the Bonosha
town is 30%. This implies that there is high gap between demand and supply. In addition,
from three years obtain data of production and consumption the average loss become 20.18%.
Furthermore, the model analysis result shows that there significant problem of pressure and
velocity in the system. The majority of junctions have negative pressure. This implies that
user are not getting sufficient water. Moreover, the problem of Bonosha town water is
insufficient yield, design problem and increasing population. The pump failure is one of
major challenge in town
PERFORMANCE ANALYSIS OF RURAL WATER SUPPLY SYSTEM: CASE STUDY OF GORDAMA AREA, ALETA WONDO WOREDA
(Hawassa University, 2023-10-25) HABTE THOMAS ABRAHAM
Unplanned water distribution is the key problems of many water authorities in developing
countries including Ethiopia. This research was conducted to carry out the assessment of
the water distribution network of Gordama area existing water supply system which is
located in Aleta Wondo Woreda of Sidama Region of Ethiopia. To examine the hydraulic
performance of the water distribution network, water GEMs modeling was adopted.
Accordingly, different reviewed reports, percentage of Non-Revenue for water, and
discussions with water service personnel were conducted to collect and analyze water losses.
The result showed that the current maximum water demand in Gordama is estimated at
5`11.06 m3/day, while small reservoirs capacity and low pump efficiency were observed in
the area water distribution networks. According to simulated results; maximum pressure
heads were examined 329.39m and 112.78m on conveyance and main distributions lines
respectively. But minimum pressure heads were computed 2.30m and 0 m on the two types
of lines. Further, the analyzed water losses result in Gordama area indicates that about
19.5% was Non-Revenue Water. However physical and apparent losses contributed small
amount as compared with non-revenue loss. Apparent losses cover 8.84% of total loss and
10.66 % was physical losses. Accordingly, for the case of Gordama community non-revenue
losses are more significant; Most of residences were not satisfied on the Gordama area. In
general, rising in water demand, small capacities of existing infrastructures and large
volume of water loss leads to intermittent water distribution in Gordama area water service.
Therefore, it is significant to rehabilitate and improve the water distribution system
capacities and provide more attention to water losses reduction policies and strategies as
appropriate intervention measures.
IMPACT OF LAND USE/LAND COVER DYNAMIC ON HYDROLOGY REGIME: A CASE STUDY IN THE UPPER BARO BASIN, GAMBELLA, SOUTHWEST ETHIOPIA
(Hawassa University, 2019-03-11) Tewodros getu engida
The principal driving forces for land use/land cover change(LULCC) are rapid increases of population and forest clearing. Those are important factors that influence the hydrological condition of a catchment. Land use/land cover change can also result in change of flood frequency, increase peak flows, base flow, and annual mean discharge. To reverses such kind of problems, assessment of hydrological condition in relation to LULC and finding solution at a watershed level is necessary. The objective of this study was to assess the impacts of LULC change on the hydrology of Upper Baro Basin using Soil and Water Assessment Tool model. The LULC change analysis was performed by using supervised classification method using ERDAS imagine 2014. The accuracy of the classified maps was assessed using error matrix of each selected period. Consequently, 92.14%, 94.63% and 95.63% were found for LULC classification of 1987 ,2002 and 2017 study years, respectively. The result show that there was a drastic decreased of grass land by15.64 % and an increase of agricultural land and settlement by 18.01% and 13.01%, respectively over period. SWAT model was adopted to perform simulation of the main hydrological component in order to finding the effect of LULCC using in 1987,2002 and 2017 and also calibration, validation and uncertainty analysis were performed using sequential uncertainty fitting (SUFI-2). The result showed that there was a reasonable agreement between observed and simulated streamflow with coefficient of determination (R2) and Nash-Sutcliffe efficiency values 0.87 and 0.76 for calibration periods 1990-2002 and 0.77and 0.72 for validation period of 2003 to 2010 respectively. Further, the model was predicting the impact of LULC change on streamflow for period 1987,2002 and 2017. Evaluation of hydrologic response unit (HRU) due to LULCC showed that mean monthly streamflow was increased by 35.8% in wet months and decreased by 21.05% in dry months between the years 1987 and 2002. While betwee 2002 and 2017, it was increased by 47.1% and 3.49% for wet and dry months, and the year 2017 and 1987, it was increased by 82.9% and 15.54% for wet and dry months respectively. InVEST model was used to assess the total soil loss potential for each LULCC, these result show that increased from 276462.8 in 1987 to 391741.2 ton/year in 2017 and the mean annual soil loss was also increased from 67.67ton/ha/year in 1987 to 70.84ton/ha/year in 2017. The trend of soil loss and sediment export indicates that an increase in LULCC. Deforestation and soil erosion problems need to be give attention urgently to maintain the stability and resilience of the ecosystem
GIS BASED GROUNDWATER POTENTIAL MAPPING AND RECHARGE 1 ESTIMATION: A CASE STUDY IN MELKAODA WATERSHED RIFT VALLEY LAKES 2 BASIN, OROMIA, ETHIOPIA
(Hawassa University, 2021-10-24) ADEM BUTA DEKEBO
The groundwater potential zones of the Melkaoda Watershed were demarcated with the help of
remote sensing and Geographic Information System (GIS) techniques. The parameters that were
considered for identifying the groundwater potential zone like geology, slope, drainage density,
geomorphic units, and lineament density were generated from satellite data and they were then
integrated with weighted overlay in ArcGIS. Suitable ranks were assigned for each category of
these parameters and weight factors were decided for them based on their capability to store
groundwater using AHP approach and then the groundwater potential zones were classified
into four categories as very low, low, high & very high. In addition, the groundwater recharge
was estimated with the help of the WetSpass model using water balance approach. The
parameters considered for this case generally included three types: hydro-meteorological
(rainfall, temperature, wind speed, PET, and GWD), bio-physical (soil, landuse, topography,
and slope), and attribute lookup (soil lookup, landuse lookup, and rain day lookup) tables. All
the hydro-meteorological parameters were interpolated in ArcGIS for grid map preparation of
each parameter and the prepared grid map was converted to ASCII file format for the effective
model run. The model performance was checked through calibration and the obtained
groundwater recharge result ranges 0.45 to 65.5 mm/year with the mean value of 32.87
mm/years and 3.4% contributed to groundwater as recharge. finally, the changes in
groundwater recharge between two simulation period was stated again with help of WetSpass
model using the LULC images of 1989 and 2018 to quantify the impacts of the LULCC. The
parameters used for this analysis were the same as those used for groundwater recharge
estimation except for the satellite image of 1989 and the LULCC analysis depicted that there
was the expansion of built-up land and agricultural land. Agricultural land and built-up land
were increased by 0.046, 2.56 rate per a year from 1989 to 2018 respectively. This paper
finalized that there was access to the groundwater potential in the Melkaoda Watershed and
this could overcome the water scarcity challenging the community in and around the area. The
recharge which has been the main source of groundwater is decreasing from time to time as the
result of this paper is indicating. Thus, to get sustainable groundwater potential, the recharge
has to be well treated by increasing groundwater recharge