Penentuan Batas DAS Tojo Berbasis GIS Menggunakan Perangkat HEC HMS 4.4 dan QGIS 3.16

Watershed delineation is the process of determining an area that contributes to the flow of rainfall (precipitation) into runoff to the outlet. The watershed delineation analysis in this study used the HEC-HMS version 4.4 and QGIS 3.16 . HEC HMS version 4.4 has GIS tools that have been directly integrated to facilitate the watershed delineation process. The study area in this research is the Tojo watershed which is located in Central Sulawesi Province. The digital elevation model (DEM) data source used is DEMNAS BIG with a spatial resolution is 8,1 meters. The results of watershed delineation using HEC-HMS 4.4 software are the same as the results of watershed delineation using QGIS 3.16 software. There is a slight difference in the watershed boundary in some parts when zoomed in. The watershed area produced by each GIS Softwares are HEC-HMS 212,583 km2, QGIS 212,5404 km2. The HEC-HMS 4.4 software gives quite good results on the boundary analysis of the Tojo watershed, so the HEC-HMS 4.4 software can also be used in other researches in the field of water resources.

​The Significance Impact Assessment of Morphological Parameters on Watershed: A Review

Watershed morphological analysis is momentous for controlling floods risk, forethought and management of the watershed area, as well as it is foremost useful to perceive catchment hydrology. Remote sensing and geographic information system are used in recent times as a tool for watershed delineation and its planning. Many types of input parameters generally use for watershed delineation such as Toposheet, ALOS, SRTM DEM, ASTER DEM and CARTOSAT DEM. Based on analysis SRTM DEM gives meticulous and clear results compared to other DEM files. Morphometric based prioritization of watershed was given in many research papers but an appropriate result of priority range was not given and this type of study confusing to evaluate the rank of priority based on its erosional behaviour. In many papers results of morphometric parameters were not indicate how to retaliate these results of morphometric parameters to a watershed. This paper deals with the implication of different values of morphometric parameters with adequate contextual information. This review paper can give useful information for the morphometric analysis of watersheds.

Application of the SWAT Model for Evaluating Discharge and Sediment Yield in the Huay Luang Catchment, Northeast of Thailand

The climate change and insufficient data of the discharge and sediment yield in the catchment system are the main cause of the conflict amongst the consumers. The application of a semi-distributed hydrologic model and geographic information system can be a solution to this conflict. This study implemented the SWAT model to estimate the discharge and sediment yield in the Huay Luang Catchment, Northeast of Thailand. The accuracy of the model was affirmed and compared with the data from the Kh103 observed station during 2008–2016 via SWAT-CUP. The study outcome suggested that the SWAT model provided favourable results compared to the observed data where R2, NSE, and PBIAS of the discharge were 0.79, 0.77, and -18.1% respectively and those of the sediment yield were 0.68, 0.65, and -22.7% respectively. Additionally, the quantitative analysis on 22 sub-catchments as the spatial map derived from the Watershed Delineation indicated that both discharge and sediment yield during 2008–2011 were higher than the regular values by 35.9% and 109.6% consecutively, whereas during 2012–2015 were lower than the regulars by 22.4% and 45.4%. In the raining season, more than 50% of the sub-catchments demonstrated 9–20 cubic meter per second of the discharge and 1,000–5,000 tons of the sediment yield, while during the drought season, both volumes in most of the catchments indicated less than 6 cubic meter per second and 1,000 tons, respectively. These happened due to the changes of the rainfall each year. Hopefully, the result and spatial information from this study could be a great contribution to the water resource management and development in any catchment with insufficient data.

Hydrological Mapping in the Luquillo Experimental Forest: New Local Datum Improves Watershed Ecological Knowledge

Streams and rivers of the Luquillo Experimental Forest, Puerto Rico, have been the subject of extensive watershed and aquatic research since the 1980s. This research includes understanding stream export of nutrients and coarse particulate organic matter, physicochemical constituents, aquatic fauna populations and community structure. However, many of the streams and watersheds studied do not appear in standard scale maps. We document recent collaborative and multi-institutional work to improve hydrological network information and identify knowledge gaps. The methods used to delimit and densify stream networks include establishment and incorporation of an updated new vertical datum for Puerto Rico, LIDAR derived elevation, and a combination of visual-manual and automated digitalization processes. The outcomes of this collaborative effort have resulted in improved watershed delineation, densification of hydrologic networks to reflect the scale of on-going studies, and the identification of constraining factors such as unmapped roadways, culverts, and other features of the built environment that interrupt water flow and alter runoff pathways. This work contributes to enhanced knowledge for watershed management, including attributes of riparian areas, effects of road and channel intersections and ridge to reef initiatives with broad application to other watersheds.

Effect of Watershed Delineation and Climate Datasets Density on Runoff Predictions for the Upper Mississippi River Basin Using SWAT within HAWQS

The quality of input data and the process of watershed delineation can affect the accuracy of runoff predictions in watershed modeling. The Upper Mississippi River Basin was selected to evaluate the effects of subbasin and/or hydrologic response unit (HRU) delineations and the density of climate dataset on the simulated streamflow and water balance components using the Hydrologic and Water Quality System (HAWQS) platform. Five scenarios were examined with the same parameter set, including 8- and 12-digit hydrologic unit codes, two levels of HRU thresholds and two climate data densities. Results showed that statistic evaluations of monthly streamflow from 1983 to 2005 were satisfactory at some gauge sites but were relatively worse at others when shifting from 8-digit to 12-digit subbasins, revealing that the hydrologic response to delineation schemes can vary across a large basin. Average channel slope and drainage density increased significantly from 8-digit to 12-digit subbasins. This resulted in higher lateral flow and groundwater flow estimates, especially for the lateral flow. Moreover, a finer HRU delineation tends to generate more runoff because it captures a refined level of watershed spatial variability. The analysis of climate datasets revealed that denser climate data produced higher predicted runoff, especially for summer months.

Analisa Erosivitas Lahan Pada DAS Batang Agam Dengan Menggunakan Model SWAT

Batang Agam River is a river that flows along Bukittinggi City, Agam Regency, Fifty Cities Regency, Tanah Datar Regency, Payakumbuh City and empties into the Batang Sinamar River. The Batang Agam River, which crosses the residential area, is mostly used for agriculture, fisheries, tourism, mining and other activities. Community activities in the area of the Batang Agam River have resulted in a decrease in the function of the river which is characterized by narrowing, silting and pollution of the river. In addition, it is influenced by the ever-changing river water discharge, land conditions and changes that occur in the river channel. In addition, the negative behavior of the community and all their activities around the river basin also triggers damage to the river. This research was conducted to determine the value of land erosivity towards changes in land use area in the Batang Agam watershed, in this study using land cover in 2010, 2014, and 2019 using the Soil and Water Assessment Tool (SWAT) model and manual calculations were carried out using the USLE method as ratio. The analysis consists of four processes, namely watershed delineation, formation of a Hydrologic Response Unit (HRU), formation of climatological data, and finally the simulation process. The results of the HRU analysis showed that the Batang Agam watershed became 7 sub-watersheds, the dominant HRU was primary forest. In the case of Batang Agam, it was found that the level of erosion hazard was in the light category and the erosion value decreased in each review year.

ESTIMATION OF ANNUAL RUNOFF AND PEAK FLOW AT NAZANIN CATCHMENT IN ERBIL, KURDISTAN REGION USING DIFFERENT APPROACHES

Runoff is excess rainfall or a portion of rainfall that flows over the watershed. In un-gauged streams, due to lack of data, many methods are used for runoff estimation. In this paper annual runoff and peak flow of Nazanin watershed were estimated at Nazanin Dam location using different methods. Soil Conservation Service (SCS) method, basin relation, (Hydrologic Engineering Center – Hydrologic Modeling System) HEC-HMS and Hydrologic engineering center (HEC-1) models were provided. The Watershed Modeling System (WMS) package was used for watershed delineation and computation of curve number. The area of Nazanin catchment is 72.14 km2, and the composite curve number is 81.3. The results of average annual rainfall estimated using the basin relationship method are more than that obtained from SCS method. The results of peak flood discharge for different return periods using different approaches such as SCS method, HEC-HMS and HEC-1 models are very close. But the results of basin relation are lower than SCS method. From the results of comparison, it was observed that HEC-HMS and HEC-1 models can be used for generation flood hydrograph at ungagged watershed.