Analysis of droughts due to the operation of water structures: Gidra river case study

The paper deals with an analysis of a drought in the small basin of the Gidra River in Slovakia due to problems with the abstraction of water from small reservoirs and ponds. A detailed hydrological assessment of the M-daily discharges for a long-term period was based on a dataset from the only gauging station on the upper part of the river. Because of the existing water structures with prescribed operations during the year, hydrometric and geodetic measurements were taken by the authors. The solution to this problem represents the conditions for the minimum required Q355 discharge in the river anytime and anywhere. This can only be solved with a master operational manual for the whole river to be able to flexibly react to the current hydrological situation.

The structural positions of the ophiolite complex in the Earth crust of the western Tien-Shan

The westernmost parts of the Tien Shan region are located between two areas of crustal suturing, formed by the closure of the Turkestan Ocean, and probably the closure of a second ocean, the Gissar Ocean. Regional correlation of these sutures, however, has been problematic due to the lack of geological and geophysical data, as well as conflicting interpretations within the literature of various geological bodies. We summarize the information about Paleozoic ophiolites of westernmost parts of the Tien Shan for the international geoscientific audience from the literature and our own unpublished data. We focus on the best-known examples of Southern Tien Shan ophiolites which are remnants of Paleo-Asian Ocean, aligned in two main belts in Uzbekistan. Ophiolites reveal a wide age spectrum ranging from the Ordovician to the Devonian on the northern slope of Southern Tien Shan, and the Early Carboniferous on the southern slope. Considering all data on these ophiolites as well as regional considerations lets us conclude that a single ocean located subduction of the Turkestan Ocean basin under the northern Karakum-Tadjik terrane caused back-arc continentalo ruisft.i ngo iunththwearGdi ssar region in Early Carboniferous resulted in the formation of a small basin with oceanic crust. By late Carboniferous/early Permian times, both oceanic basins were subducted.

Estimation of Terrestrial Water Storage Changes at Small Basin Scales Based on Multi-Source Data

Terrestrial water storage changes (TWSCs) retrieved from the Gravity Recovery and Climate Experiment (GRACE) satellite mission have been extensively evaluated in previous studies over large basin scales. However, monitoring the TWSC at small basin scales is still poorly understood. This study presented a new method for calculating TWSCs at the small basin scales based on the water balance equation, using hydrometeorological and multi-source data. First, the basin was divided into several sub-basins through the slope runoff simulation algorithm. Secondly, we simulated the evapotranspiration (ET) and outbound runoff of each sub-basin using the PML_V2 and SWAT. Lastly, through the water balance equation, the TWSC of each sub-basin was obtained. Based on the estimated results, we analyzed the temporal and spatial variations in precipitation, ET, outbound runoff, and TWSC in the Ganjiang River Basin (GRB) from 2002 to 2018. The results showed that by comparing with GRACE products, in situ groundwater levels data, and soil moisture storage, the TWSC calculated by this study is in good agreement with these three data. During the study period, the spatial and temporal variations in precipitation and runoff in the GRB were similar, with a minimum in 2011 and maximum in 2016. The annual ET changed gently, while the TWSC fluctuated greatly. The findings of this study could provide some new information for improving the estimate of the TWSC at small basin scales.

MORPHOGRAPHIC STUDY OF BOIULUI VALLEY HYDROGRAPHIC BASIN

The aim of the present paper is to determine the morphometric parameters and features of Boiului Valley hydrographic basin. The basin is located in a karst area, in Pădurea Craiului Mountains, Romania, which makes it special, as the rivers flow through soluble rocks. We selected a small basin in order to analyse its morphometric elements and check if the morphometric laws of hydrographic basins are respected in the same way by the rivers flowing in karst areas. We applied the classical working method, that is processing the information from the topographic maps and with the help of the ArcGis soft we managed to measure the major morphometric indicators: the surface of the basin, the area, the shape factor, the length and width of the basin, drainage basin asymmetry factor and sinuosity index.

Modeling of the Geological Probability Procedure for the Prediction of High Flows in Small Streams, Case Study of Medvednica Mt., Croatia

Floods are defined by maximum water levels or flow of high-water waves. Here, we defined the deterministic method for the calculation of the probability of a high discharge event, named as the Probability Of Success (POS). The POS method previously developed for petroleum subsurface systems has been modified for the surface hydrological system with the purpose of flood prediction. The case study of this research is the small basin of Kašina Stream on Medvednica Mt. (NW Croatia). The data are obtained upstream from the hydrological station Gornja Kašina. The POS model is defined by four categories. Each geological category is described with accompanied events and probabilities. Floods are defined by four categories: total precipitation, total water flow, basement, and maximal water capacity in soil. The categories total precipitation and basement were divided into two sub-categories each: quantity and duration; porosity and soil depth. Data are collected for a hydrometeorological event, namely an intensive convective storm on 24–25 July 2020, when Zagreb was locally hit by heavy urban floods. The presented probability method yielded a probability of 1.76% that such an event could happen to the station. However, the flooding was not recorded. A comparison of the real event and the predicted probability supported the adequacy and applicability of the method, showing it has high reliability. The presented probability model could be easily applied, with small modifications, to the entire area of Northern Croatia for the prediction of small basin flooding events.

Design of rain gauge network using radar and road network

<p>Uncertainty in the gauged network can lead to inaccuracies in dam operations. Entropy is a well-known measurement of uncertainty. Goesan Dam has a small basin area and is affected by a small amount of precipitation, and Hwacheon Dam is contained outside the territory of South Korea, making it difficult to observe the water flow. The observed gauged precipitation and radar data on rainy days were considered between 2018 and 2019. Choosing appropriate radar were performed based on the priority of the rainfall gauge network using conditional entropy. This is because the rainfall gauge network is the actual precipitation and it can only cover certain points. However, the radar is the cloud reflectivity of a large area. Therefore the location of additional rain spots was selected through conditional entropy of highly consistent radar data. Nevertheless, there might be difficulties in installing gauged equipment in reality. So the optimal rainfall network was designed in consideration of the road network. As a result, the uncertainty of precipitation in Goesan Dam and Hwachoen Dam could be decreased by 63.3% and 67.9% respectively when three additional potential rain points were operated without any restriction. The uncertainty in the Goesan Dam basin and Hwachoen Dam would be reduced up to 55.3% and 65.0% when three additional potential rain points were installed nearby the road network. Therefore, through the proposed method, an optimal rainfall network can be designed by balancing cost and uncertainty.</p><p>This work was supported by KOREA HYDRO & NUCLEAR POWER CO., LTD (No. 2018-Tech-20)</p>