KARAKTERISTIK HIDROLOGI DAN DAMPAKNYA TERHADAP BANJIR DAERAH ALIRAN SUNGAI JAMBO AYE DI ACEH INDONESIA (Hydrological Characteristics And Its Impact On Flood Jambo Aye Basin In Aceh Indonesia)

Daerah Aliran Sungai (DAS) mengalami peningkatan kerusakan akibat hubungan dan interferensi manusia yang berdampak pada kesetimbangan hidrologi sehingga terjadi bencana. Bencana banjir yang merupakan bencana hidrologi rutin terjadi di DAS Jambo Aye. Penelitian ini bertujuan untuk menganalisa hubungan karakteristik hidrologi DAS Jambo Aye terhadap potensi dan kejadian banjir di wilayah DAS Jambo Aye. Karakeristik kemiringan lereng, pergerakan tanah, analisis kelompok hidrologi tanah (HSG), Antecedent Precipitation Index (API) dan kurva limpasan digunakan sebagai indikator hidrologi untuk mengidentifikasi potensi banjir yang terjadi di DAS Jambo Aye. Analisis menunjukkan DAS Jambo Aye termasuk wilayah yang berpotensi mengalami banjir. Potensi banjir genangan terdapat di wilayah hilir yang mempunyai karakteristik lereng landai (12%), kapasitas infiltrasi sangat lambat (37,95%), nilai kurva limpasan tinggi (17%) dan tingkat kebasahan yang tinggi (26%). Banjir bandang berpotensi terjadi di wilayah hulu yang mempunyai karakteristik lereng curam, adanya pergerakan tanah dan curah hujan yang tinggi. Pengelolaan DAS perlu dilakukan di DAS Jambo Aye mengingat kejadian banjir yang sering terjadi.

HYDROLOGICAL CHARACTERISTICS OF THE DNIESTER ESTUARY BY SURVEYS IN THE SUMMER’S OF 2003–2019

Problem Statement and Purpose. The Lower Dniester delta and the Dniester estuary are very important because they are natural filters of the river water from pollution and suspended matter, as well as they are the habitat of a large number species of flora and fauna. The construction of reservoirs on the Dniester River in past completely changed the hydrological regime of the river itself and of the Dniester estuary. For these reasons a constant environmental monitoring of the aquatic environment are required. Since 2002 Odessa I. I. Mechnikov National University has been carrying out a wide range of environmental studies in the Dniester estuary, one of aspects of which is observation of hydrological characteristics. The purpose of this paper is to study long-term changes in transparency, temperature and electrical conductivity of the Dniester estuary water in the summer periods of 2003–2019. Materials & Methods. Measurements of transparency, temperature and electrical conductivity of water in the Dniester estuary in the indicated years were carried out according to standard methods at 19 ecological stations. Statistical processing, analysis and mapping of the measurements results were conducted in EXCEL, ARCGIS, SURFER software’s. Data analysis was based on a graphical representation of the spatial distribution of characteristics, as well as by identifying the features of long-term changes in these characteristics. Main Results and Conclusions. On the basis of the summer surveys during 2003–2019 more than double decrease of water transparency mean values in the Dniester estuary has been established. It was found that the maximum transparency values were observed in the central parts of the estuary, far from settlements. For theseyears, an increase of the mean water temperature for the estuary northern part and its decrease in the middle and southern parts has been recorded. Also, for the summer period of these years, an increase of the mean water electrical conductivity in all parts of the estuary was established. The established features of spatial distribution of hydrological characteristics indicate to the river runoff, intrusion of seawater into the estuary, and wind activity as the determining factors in formation of the estuary hydrological regime. Recorded long-term trends of the means transparency values decreasing and the means temperature and electrical conductivity increasing of the Dniester estuary water in the summer of 2003–2019 are considered as consequences of the river discharge decreasing due to long-term climatic changes over Europe and man regulation of river flow.

Analisis Karakteristik Hidrologi DAS Krueng Aceh, Provinsi Aceh (Studi Kasus Sub DAS Krueng Jreu dan Sub DAS Krueng Khea)

Abstrak. Perilaku air (hidrologi) sungai dalam suatu DAS dipengaruhi oleh penggunaan lahan sebagai akibat adanya aktivitas manusia. DAS Krueng Aceh merupakan salah satu DAS yang terdapat di Provinsi Aceh menjadi sumber air utama bagi penduduk Kota Banda Aceh dan Kabupaten Aceh Besar di Provinsi Aceh. Luasan tutupan lahan berupa hutan primer saat ini semakin berkurang luasannya. Penelitian ini bertujuan menganalisis karakteristik hidrologi Sub DAS Krueng Jreu dan Krueng Khea di DAS Krueng Aceh dan pengaruhnya dengan perubahan tutupan lahan. Hasil pengolahan data diperoleh bahwa limpasan permukaan tertinggi pada Sub DAS Krueng Jreu terjadi sebesar 2.178,3 mm/bulan yaitu pada bulan Januari tahun 2015 dan limpasan terendah terjadi pada bulan Maret tahun 2014 yaitu sebesar 1 mm/bulan. Sedangkan pada Sub DAS Krueng Khea limpasan permukaan terbesar yaitu 204 mm/bulan yang terjadi pada bulan Juli tahun 2015 sedangkan limpasan terkecil sebesar 4,9 mm/bulan yang terjadi pada bulan Agustus tahun 2018. Tidak terjadi perubahan penutupan lahan yang signifikan pada kedua Sub DAS dari tahun 2014 sampai dengan 2018.Analysis of Hydrological Characteristics of the Krueng Aceh Watershed, Aceh Province (Case Study of the Krueng Jreu and Krueng Khea sub-watersheds)Abstract. The behavior of river water (hydrology) in a watershed is not only influenced by land use as a result of human activities. Krueng Aceh watershed is one of the watersheds in Aceh Province. The watershed is the main water source for residents of Banda Aceh City and Aceh Besar District in Aceh Province. The condition of land cover in the form of primary forest is currently decreasing in area. This study aims to analyze the hydrological characteristics of the Krueng Jreu and Krueng Khea watersheds in the Krueng Aceh watershed and their effect on land cover changes. From the results of data processing, it was found that the highest surface runoff in the Krueng Jreu watershed occurred at 2,178.3 mm/month in January 2015 and the lowest runoff occurred in March 2014 at 1 mm/month. While in the Krueng Khea Sub-watershed the largest surface runoff was 204 mm/month which occurred in July 2015 while the smallest runoff was 4.9 mm/month which occurred in August 2018. There was no significant change in land cover in the two sub-watersheds from 2014 to 2018.

Hydrotechnical arrangements influence on morphological and hydrological characteristics of Crişul Negru River and its tributaries - Western Apuseni Mountains, Romania

The anthropic interventions on riverbeds and banks have a direct and irreversible influence on the flow regime, primarily by changing the hydraulic characteristics of rivers, like channel slope and/or geometry, channel roughness, flow depth, consequently water velocity, propagation time of floods, etc. In the Upper Basin of the Crişul Negru River, the first hydro-technical arrangements were made in the 18th and 19th centuries, mainly for flood mitigation and swampy areas amelioration. But the most important and extensive works were designed following the exceptional floods of 1980-1981 (consolidations of banks, embankments, regularizations, bottom sills, etc.) and at the end of the 20th century. The purpose of the paper is to emphasize the effects of the hydro-technical works on both the morphology of the riverbed and the flow regime (average, minimum and maximum flow) of the most affected rivers in the study area. The data utilized are elevation profiles, stages and discharges recorded on more than 40 years at four gauging stations, namely including periods before and after the execution of the extensive works. The positive and negative influences of the arrangements are highlighted through statistical analysis and trend detection in data series, corroborated with the commissioning of the hydro-technical works and the evolution of rivers' morphology.