Investigation of ecological environment and assessment of ecological security in Tieshan Reservoir watershed

In this study, based on the “Driver-Pressure-State-Impact-Response” (DPSIR) assessment model, an assessment index system aming at the Tieshan Reservoir watershed was established from 4 aspects including social-economic impact, ecological subsystem, ecological service subsystem, regulation and management. Eighteen major items containing 55 indexes were selected in the assessment index system. Furthermore, the ecological security index (ESI) was calculated, and the deviation degree of reservoir ecological safety from the standard state was assessed. Results showed that ecological security index of Tieshan Reservoir watershed is 89, ecological security level is I , indicating security. The low security indexes of total phosphorus and total nitrogen were the major disadvantage factors that affected the ecological security of Tieshan Reservoir watershed, including rural life pollution and farmland runoff pollution. In addition, long-term mechanism of protection and development has not been formed yet, which also restricts the economic growth. Strengthening the formulation of laws and regulations on environmental protection, tamping the basic capacity building of water pollution control, developing ecological agriculture and green tourism are the important ways to improve the ecological security and realize the sustainable development of Tieshan Reservoir watershed.

Evaluating the Landslide Stability and Vegetation Recovery: Case Studies in the Tsengwen Reservoir Watershed in Taiwan

The sediment yield from numerous landslides triggered in Taiwan’s mountainous regions by 2009 Typhoon Morakot have had substantial long-term impacts on the evolution of rivers. This study evaluated the long-term evolution of landslides induced by 2001 Typhoon Nari and 2009 Typhoon Morakot in the Tsengwen Reservoir Watershed by using multiannual landslide inventories and rainfall records for the 2001–2017 period. The landslide activity, vegetation recovery time, and the landslide spatiotemporal hotspot analyses were used in the study. Severe landslides most commonly occurred on 35–45° slopes at elevations of 1400–2000 m located within 500 m of the rivers. The average vegetation recovery time was 2.29 years, and landslides with vegetation recovery times exceeding 10 years were most frequently retrogressive landslide, riverbank landslides in sinuous reaches, and the core area of large landslides. The annual landslide area decline ratios after 2009 Typhoon Morakot in Southern Taiwan was 4.75% to 7.45%, and the time of landslide recovery in the Tsengwen reservoir watershed was predicted to be 28.48 years. Oscillating hotspots and coldspots occupied 95.8% of spatiotemporal patterns in the watershed area. The results indicate that landslides moved from hillslopes to rivers in the 2001–2017 period because the enormous amount of sediment deposited in rivers resulted in the change of river geomorphology and the riverbank landslides.

DYNAMICS PATTERNS OF INFLOW IN THE RESERVOIR THAT OPERATED FOR TWO DECADES

Climate change in the past 20 years brings significant alteration in the earth surface. It affects extremely anomaly temperature, such as the ENSO, IOD, and SOI phenomena. The Pacific Ocean Region, the Indian Ocean Region, and the Darwin – Tahiti Region undergo an increase and a decrease in the sea surface temperatures (SST); thus, it can lead to seasonal change in Indonesia. Due to ENSO, IOD, and SOI, climate change also highly affects the operation pattern of reservoirs, food production, and other commodities. This research used SST data (Nino 1.2, Nino 3, Nino 3.4, Nino 4, IOD West, IOD East, and SOI) from National Oceanic and Atmospheric Administration (NOAA) and rainfall data from 1998 to 2018 of nine stations at Wonogiri Reservoir watershed. Trend analysis of the SST index indicated an increase in trend SST index. Trend analysis of monthly rainfall average at Wonogiri Watershed area indicated a decrease in January, March, April, May, June, July, August, and October, while it increased in February, September, November, and December. Multiple linear regression analysis with the stepwise regression method indicated that during the rainy season, the rainfall at Wonogiri Watershed and Inflow at Wonogiri reservoir were influenced by the SST index (Nino 1.2, Nino 3, Nino 3.4, Nino 4). Meanwhile, during the dry season, the rainfall at Wonogiri Watershed and the Inflow at Wonogiri reservoir were influenced by the SST index (IOD West, IOD East, and SOI). With monthly correlations between SST and rainfall data that have a dynamic characteristic, it can be used to calculate the inflow probability distribution in optimizing reservoir operation patterns.

Optimization Model of Reservoir Operating Pattern Based on the Adaptive Inflow for Climate Change

Urban Climate change in the past 40 years carries significant effects on the earth's surface. It shows an effect of extremely anomaly temperature because of such phenomenons as ENSO, IOD, and SOI. Thus, it can lead to seasonal change in Indonesia that affects the reservoir inflow and impacts the reservoir's operation pattern for managing power plant, irrigation, and raw water supply. This research used the relation between SST data (Nino 1.2, Nino 3, Nino 3.4, Nino 4, IOD West, IOD East, and SOI index) from NOAA and rainfall data from 1998 to 2018 in 9 stations at Wonogiri Reservoir Watershed from BBWS Bengawan Solo. With multiple linear regression analysis with a stepwise regression method, it indicated that the rainfall at Wonogiri Watershed and Inflow at Wonogiri reservoir was influenced by the SST index (Nino 1.2, Nino 3, Nino 3.4, Nino 4). Meanwhile, during the dry season, the rainfall at Wonogiri Watershed and the Inflow at Wonogiri reservoir were influenced by the SST index (IOD West, IOD East, and SOI). The rainfall and SST are related to being modeled for the probability of inflow distribution in each period (every 15 days). This inflow model influenced by climate change is to be used for the optimization model of reservoir operating pattern with Stochastic Model. The result that scenario 6 have the highest benefit, highest performance in the reliability and resiliency value in the simulation for a period between years 1979-2018.

Caracterização Morfométrica e Uso e Ocupação do Solo em Bacia Hidrográfica do Semiárido Pernambucano

Este trabalho investigou a caracterização de uma bacia hidrográfica do Semiárido de Pernambuco e os efeitos da estiagem nas condições de uso e ocupação do solo por meio da adoção de geotecnologias aplicadas à gestão dos recursos hídricos. Para tanto, foram obtidas as imagens de altimetria pela Embrapa e realizada análise para caracterização morfométrica com o software QGIS e a extensão Terrain Analysis Using Digital Elevation Models – TauDEM. Além disso, se utilizaram as imagens de uso e ocupação do solo da plataforma do MAPBIOMAS BRASIL referente aos anos de 2011 e 2018 para analisar as modificações ocorridas durante o período de estiagem. A Bacia Hidrográfica do açude Cachoeira II apresenta forma alongada, o que indica uma baixa tendência a enchentes em condições normais de precipitação, baixa sinuosidade ocasionando uma maior velocidade de escoamento da água até o exutório e apresenta predominância das seguintes classes de relevo: suave ondulado e ondulado. Os dados de uso e ocupação demostraram que a maior ocupação da bacia é de formação do bioma Caatinga. A estiagem no período de 2012 a 2017 junto com a diminuição das áreas de caatinga e o aumento das áreas de pastagem favoreceram a ocorrência de erosão e o transporte de sedimentos na bacia, contribuindo para diminuição do açude Cachoeira II. Morphometric characterization and land use and occupation in a watershed in the semiarid of Pernambuco ABSTRACTThis work investigated the characterization of a watershed in the Semiarid of Pernambuco and the effects of the drought on the conditions of use and occupation of the soil through the adoption of geotechnologies applied to the management of water resources. For that, the altimetry images were obtained by Embrapa and an analysis for morphometric characterization was performed with the QGIS software and the Terrain Analysis Using Digital Elevation Models - TauDEM extension. In addition, the images of land use and occupation on the MAPBIOMAS BRASIL platform for the years 2011 and 2018 were used to analyze the changes that occurred during the drought period. The Cachoeira II reservoir watershed has an elongated shape, which indicates a low tendency to flooding under normal precipitation conditions, low sinuosity causing a faster flow of water to the exutory and presents predominance of the following relief classes: smooth undulating and wavy. The use and occupation data showed that the largest occupation of the basin is the formation of the Caatinga biome. The drought in the period from 2012 to 2017 together with the decrease in the caatinga areas and the increase in the pasture areas favored the occurrence of erosion and the transport of sediments in the basin, contributing to the decrease of the Cachoeira II reservoir.Keywords: MAPBIOMAS, QGIS, SRTM