Banjir Bandang di DAS Batang Kuranji Kec. Kuranji Kotapadang dengan Sistem Informasi Geografis (Sig)

The research aims to map hazard flash flood sand Inundation mapping the spatial distribution(affected by) flash floods and analyze the factors causing flash floods in Batang Kuranji Watershed Sub- District Kuranji Padang. The method used is a 3D analysis of data raster DEM, topographic slope, Slope, flood elevation data, and river network data, for mapping the spatial distribution affected by the flash floods using survey methods to map land units as mapping unit. GPS tracking is then performedin the field to produce spatial distribution maps Inundation (affected by) flash floods and flash floods causing factor data were analyzed using the scoring methodo fland characteristics as determinants offlash flood hazard. From this research, the proportion of flood hazard zones with high hazard category with abroad zone of 1320 ha, or 6,15% of the region Batang Kuranji. Medium hazard zones are an area of 1243 ha or 5,7% of the region Batang Kuranji, and low hazard zones in the study region has an area of 18 885ha with aproportion of 88,15% of the total land area ofresearch Batang Kuranji and spatial distribution of the inundations flash floods in the area along Kuranji watershed in Koto Tangah subdistrict, Kuranji subdistrict, Nanggalo subdistrict, North Padang subdistrict, and Pauh subdistrict. Causing factor flash flood in the research area are mass movement that of caused landform, slope, slopeform, long of slope, and geomorphology process

WATERSHED MANAGEMENT BETTAHALASURU USING GIS AND REMOTE SENSING

Satellite remote sensing data with geographic information system has a pragmatic approach to map and generate spatial input layers of predicting response behavior and yield of watershed. Hence, in the present study an attempt has been made to understand the hydrological process of the command area at the watershed level by drawing the inferences from soil loss estimation. The study area chosen for the present study is Bettahalasuru command area situated in Bengaluru North lies geographically between 13°10'8"N and 13°9'12"N latitude and 77°35'58"E and 77°37'35"E longitude and toposheet No:57 G/12. It covers an area of 3.8 Sqkm and perimeter of 7.89km. Top few centimeters of the soil will usually be fertile, which is very important for the agricultural practices. Soil loss estimation was carried out in order to assess the erosion rate. If the erosion rate is severe, immediate steps should be undertaken to conserve the soil. Several methods were suggested in the past but due to its robustness, USLE (Universal Soil Loss Estimation) model has been adopted in the present study. The weighted soil erosion estimated was 16.53 t/ha/year which is Moderate soil loss. Hence should adopt conservation practices to reduce soil loss

Kajian Hidrologi Debit Puncak Penyebab Banjir Bandang Menggunakan Pemodelan Hidrograf Satuan Sintesis-SCS (HSS-SCS)

Siklus hidrologi merupakan hal terpenting dalam memahami proses fisik yang mengendalikan distribusi dan pergerakan air. Salahsatu proses siklus hidrologi yang paling berbahaya adalah hujan karena mampu menyebabkan bencana di lingkungan perairan seperti banjir dan banjir bandang. Penelitian ini merupakan sebuah kajian hidrologi di Sub-DAS Bt. Kuranji, Provinsi Sumatera Barat. Tujuan penelitian ini adalah mengetahui debit puncak penyebab banjir bandang akibat curah hujan harian melalui analisis karakteristik hidrograf banjir (HSS) menggunakan pemodelan hidrologi berbasis SIG dan HEC-HMS. Data yang digunakan yaitu DEM IFSAR, data hujan selama 38 tahun, dan citra satelit Quickbird. Data diolah menggunakan perangkat lunak HEC-HMS dan HEC-GeoHMS pada Arc-GIS untuk mendapatkan nilai hujan rerata kawasan (MAP), SCS-CN dan Hidrograf banjir dari debit puncak. Hasil penelitian menunjukkan bahwa hujan terkosentrasi selama 3 jam dengan Puncak hujan efektif (Pe) pada periode ulang 2, 5, 10, 20, 50, dan 100 tahun rata-rata terjadi antara jam ke-2 dan jam ke-3 turunnya hujan. Debit puncak (Q) tiap periode ulang secara berurutan yaitu 168,4 m3/dt, 287,9 m3/dt, 381,5 m3/dt, 479,6 m3/dt, 616,4 m3/dt, dan 724,9 m3/dt

SWAT model application to estimate runoff for ungauged arid catchments experiencing rapid urbanisation: Riyadh case study

The built-up area of Riyadh city increased from approximately 4.5 km² in 1950 to reach approximately 1,600 km² by 2022 spreading over vast areas of the Wadi Hanifah and Wadi As Silayy catchments. The rapid growth of the city has led to repeated urban flooding. There is an urgent need to study surface runoff and how it is affected by land-use/land-cover (LULC) change in the ungauged catchments of the city. This study addressed that knowledge gap and was the first attempt to calibrate, validate, and run a semi-distributed model to simulate runoff depths and discharge rates for Riyadh's main catchments and sub-basins using five historical and five future scenarios. The Soil Water Assessment Tool (SWAT) was used for the modelling. TerraClimate evapotranspiration (ET) data was used to calibrate the SWAT model owing to a dearth of observed runoff data across Riyadh city. The literature review revealed that the use of Terraclimate ET to calibrate SWAT models is still very limited so far. The only previous study found is Herman et al. (2020). Therefore, this study is fairly unique in that it uses Terraclimate ET to successfully calibrate and validate a SWAT model. A one-by-one sensitivity analysis was performed to evaluate the impact of changing parameter values on the runoff simulations. The results indicated that simulated runoff sensitivity to selected parameter values in the calibrated SWAT models was minimal in the study area, where the relationships between simulated annual runoff and max and min runoff resulted in a very strong R2 (0.9998). The calibrated and validated SWAT models were run monthly and daily to simulate runoff and to assess the impact of several LULC change scenarios on surface runoff for both historical and future periods. The results of SWAT models of the main catchments and sub-basins located within the built-up areas demonstrated the positive effect of Riyadh’s development on runoff and discharge values for historical LULC scenarios and LULC 2030 probabilities scenarios. But the increasing rates of simulated runoff were not the same for all sub-basins due to the different proportions of urbanisation in each sub-basin. On the contrary, simulation results showed that runoff depths and discharge rates in sub-basins outside the boundaries of the built-up areas of Riyadh did not have significant changes when using historical LULC scenarios or LULC 2030 probabilities scenarios. The increase in runoff depths and discharge rates in the sub-basins reflected the direct influence of the urbanisation process on surface runoff. The increase in simulated surface runoff and discharge can be attributed mainly to the potential decrease of relatively permeable barren lands and the increase of impervious urban surfaces. Limitations faced during the SWAT model development suggest further research should aim to get detailed and accurate runoff estimates in Riyadh city to sufficiently assist decision-makers and city officials to adopt runoff and flood hazard management schemes in the city

SWAT model application to estimate runoff for ungauged arid catchments experiencing rapid urbanisation: Riyadh case study

The built-up area of Riyadh city increased from approximately 4.5 km² in 1950 to reach approximately 1,600 km² by 2022 spreading over vast areas of the Wadi Hanifah and Wadi As Silayy catchments. The rapid growth of the city has led to repeated urban flooding. There is an urgent need to study surface runoff and how it is affected by land-use/land-cover (LULC) change in the ungauged catchments of the city. This study addressed that knowledge gap and was the first attempt to calibrate, validate, and run a semi-distributed model to simulate runoff depths and discharge rates for Riyadh's main catchments and sub-basins using five historical and five future scenarios. The Soil Water Assessment Tool (SWAT) was used for the modelling. TerraClimate evapotranspiration (ET) data was used to calibrate the SWAT model owing to a dearth of observed runoff data across Riyadh city. The literature review revealed that the use of Terraclimate ET to calibrate SWAT models is still very limited so far. The only previous study found is Herman et al. (2020). Therefore, this study is fairly unique in that it uses Terraclimate ET to successfully calibrate and validate a SWAT model. A one-by-one sensitivity analysis was performed to evaluate the impact of changing parameter values on the runoff simulations. The results indicated that simulated runoff sensitivity to selected parameter values in the calibrated SWAT models was minimal in the study area, where the relationships between simulated annual runoff and max and min runoff resulted in a very strong R2 (0.9998). The calibrated and validated SWAT models were run monthly and daily to simulate runoff and to assess the impact of several LULC change scenarios on surface runoff for both historical and future periods. The results of SWAT models of the main catchments and sub-basins located within the built-up areas demonstrated the positive effect of Riyadh’s development on runoff and discharge values for historical LULC scenarios and LULC 2030 probabilities scenarios. But the increasing rates of simulated runoff were not the same for all sub-basins due to the different proportions of urbanisation in each sub-basin. On the contrary, simulation results showed that runoff depths and discharge rates in sub-basins outside the boundaries of the built-up areas of Riyadh did not have significant changes when using historical LULC scenarios or LULC 2030 probabilities scenarios. The increase in runoff depths and discharge rates in the sub-basins reflected the direct influence of the urbanisation process on surface runoff. The increase in simulated surface runoff and discharge can be attributed mainly to the potential decrease of relatively permeable barren lands and the increase of impervious urban surfaces. Limitations faced during the SWAT model development suggest further research should aim to get detailed and accurate runoff estimates in Riyadh city to sufficiently assist decision-makers and city officials to adopt runoff and flood hazard management schemes in the city