Effect of Land Cover Change on Discharge in Pangkajene Watershed

Land cover changes that occur impact on the hydrological conditions in a watershed. The hydrological condition referred to as the output quantity of the watershed is discharge which describes the quantity of water. This study aims to determine the effect of land cover change on streamflow in the Pangkajene Watershed. The results showed that there was a decrease in average peak discharge in January of 213.73 m3/s to 95.79 m3/s in the same month in 2017. Land cover changes that occurred were mixed dryland farming of bushes into paddy fields, shrubs, and settlements while forests was experienced a slight change to open land by 0.69 ha. The increase in the area of paddy fields and shrubs as large as it causes the average discharge to decrease. A decrease in the average monthly discharge in the Pangkajene watershed due to rainfall on its way into the rice irrigation water experienced process begin from, is accommodated, evaporates, so that the flow up to the river becomes small. In addition, rainfall in 2009 which is the input of the Pangkajene watershed is higher than in 2017.

Soils of the southeast slope of the Great Caucasus, their morphogenetic structure and diagnostic indicators

The article deals with the morphogenetic indications and modern diagnostic parameters of the characteristic soil types profile on the basis of the climatic and hydrological condition and International WRB system besides the short physical–geographical state, geomorphological and physiological structure.

Assessment of Hydro-Meteorological Condition of Kathmandu (Nagdhunga)-Naubise-Mugling Road and Bridges

The Kathmandu (Naghdhunga)-Naubise-Mugling (KNM) road has passed hilly area from Nagdhunga to Naubise (about 13%) after passing Naubise the road alignment passes river valley of the Mahesh Khola and Trishuli River, initially the road alignment follows on left bank of the Mahesh Khola valley upto Galchhi before meeting with Trishuli River. After Galchhi, road alignment follows the left bank of the Trishuli River valley upto Mugling (about 87%). The present study deals with the hydrological condition of the KNM road by analysing the existing hydro-meteorological data, reviewing the reports/documents of the previous studies and visiting the study area. The annual rainfall of the study area is found to be of increasing pattern. It is necessary to construct new crossing structures along with replacing some of the existing culverts in the existing road. Existing side drains are more or less adequate but the capacity might to be increased during he improvement works. In the proposed new alignment 113 cross drains are necessary to construct and proposed side drains will be adequate for passing the design flood. Some of the stretches of the existing road are very close to the river and are vulnerable of being toe cutting and flooding from the river.

Development and assessment of rules to parameterise the ACRU model for design flood estimation

Design flood estimation (DFE) is essential in the planning and design of hydraulic structures. In South Africa, outdated methods are widely applied for DFE. In this paper the potential of a continuous simulation modelling (CSM) approach to DFE in South Africa, using the daily time-step ACRU agrohydrological model, is investigated. The paper focuses on the links and similarities between the SCS-SA and ACRU models and the subsequent preliminary investigations that were undertaken to account for and incorporate the land cover classes, including land management practices and hydrological condition, of the SCS-SA model into the ACRU CSM approach. The approach to this study was to investigate how design volumes simulated by the SCS-SA model for various land management practices or conditions could be simulated by the ACRU model. Since peak discharge estimation in both models is directly dependent on simulated volumes, this preliminary study focused only on design runoff volumes, with subsequent investigations on peak discharge required in future research. In the absence of observed data, design runoff volumes and changes in design runoff volumes, as simulated by the SCS-SA model, were used as a substitute for observed data, i.e., as a reference, to achieve similar design runoff volumes and changes in design volumes in the ACRU model. This was achieved by adjusting relevant input parameters in the ACRU model to represent the change in management practice or hydrological condition, as represented in the SCS-SA model. Following a sensitivity analysis of relevant ACRU parameters, calibration of 2 selected parameters against SCS-SA CN values for selected land cover classes was performed. A strong linear relationship (R2 = 0.94) between these ACRU parameters and SCS-SA CNs for selected land cover classes was found and consequently specific rules and equations were developed to represent SCS-SA land cover classes in ACRU. Recommendations are made to further validate and verify the approach and to further the development of a CSM system for DFE in South Africa.

Effects of dams on river flow regime based on IHA/RVA

The river hydrologic regime is a driving force of the river ecosystem. Operation of dams and sluices has significant impacts on rivers’ hydrological situation. Taking the example of the Shaying River, the Jieshou hydrologic section was selected to study the influence of the sluice and all its upstream dams on the hydrologic regime. Using 55 years of measured daily flows at Jieshou hydrologic station, the hydrological date were divided into two series as pre- and post-impact periods. Based on the IHA, the range of variability in 33 flow parameters was calculated, and the hydrologic alteration associated with dams and sluices operation was quantified. Using the RVA method, hydrologic alteration at the stream gauge site was assessed to demonstrate the influence of dams on the hydrological condition. The results showed that dams have a strong influence on the regime; the river eco-hydrological targets calculated in this study can afford some support for water resources and ecosystem management of Shaying River.