Incorporation Groundwater Recharge with AVSWAT Model Streamflow by Using Water Table Fluctuation

This research investigated contribution of sustainable management water resources in the Upstream Lesti Watershed. The main objective of this research predicted recharge of groundwater using water table fluctuation (WTF). The groundwater recharge prediction will be added as a result from deep aquifer with the performance of AVSWAT (Arc View Soil Water Assesment Tool) model by comparing observed streamflows with simulated streamflows at outlet. The water table fluctuation method from 4 well was used in the Upstream Lesti Watershed to evaluate seasonal and annual variations in water level rise and to estimate the groundwater recharge prediction (deep aquifer). Based on standard values of specific yield and water level rise, the groundwater recharge prediction from the Upstream Lesti Watershed at the outlet of sub basin 39 was 736 mm in 2007; 820,9 mm in 2008; 786,7 mm in 2009; and 306,4 mm in 2010, respectively. Keyword : AVSWAT, Groundwater Recharge, Water Table Fluctuation, Streamflo

Modeling Irrigation Water Requirement of Mixed Crop with Coupled Smart Irrigation System and System Dynamic Model

Water is a key component in the two biggest economic drivers of Taiwan, i.e., the semiconductor and agricultural industries. Agricultural water accounts for 70% of the total water usage of the nation. During drought situations, the allocation and utilization of agricultural water usage become an important issue where farmers pump groundwater to supply the irrigation deficit from surface water, which ultimately impacts regional groundwater levels. Thus, there is a need to find a way to address its field water consumption during droughts; one way is a smart irrigation water management system. In this study, a smart irrigation water management model coupled with a system dynamic model (VENSIM) was developed for mixed crops in Central Taiwan by reducing 50% of the planned irrigation. Results can be applied as a solution to water shortage during droughts with alternate frequent adjustment of water gates to ensure water supply to tail end users

Quantitative Analysis Disasters of Typhoons (1946-2000) and Heavy Storms (1959-2000) in Taiwan

臺灣處亞熱帶，並位於西太平洋颱風區，每年七月至十月為颱風侵襲的主要期間，平均每年有3-5個颱風與多次豪雨侵，根經濟部水利署統計近13-16年的颱風豪雨資料發現每年平均成3000閻房屋受損，約有128億元金額損失有於此，本研究蒐集統計處理完烕的各項颱風豪雨災害調查資料，配合颱風豪雨的雨分進行交叉比對量化分析，求得彼此間的關連性，以了解各項因子對災害發生與否量級之影響度然後配合各項災害紀錄，建立彼此間的因果關係，完成不同雨型態與災害分析。本研究果發現，不同颱風路徑會對各造成不同程度的累積降雨及災情依據統計結果，颱風災害造成臺灣地區林漁業、人員傷亡及房屋損，每場均損失約20億元右。若將臺灣分成北中南東四區域來看，當颱風累積降雨在北部地區達200mm以上，中部地區達300mm以上，南部地達350mm以上，東部地區達300mm以上時，各地區淹水率即高達40%。「秋颱」爲秋天從臺灣南部北上之颱風，佔秋季颱風比例約60%，且由颱風本身逆時鐘方向旋轉，加上北季風影響，故不其從臺灣西岸或東岸掠過，雨均集中於東部「西北颱」為從灣北部經過之颱風，則會造成臺灣北部及中部集中降雨。 Taiwan, located at the subtropical zone in western Pacific Ocean, suffers the damage from 3.5 typhoons on average yearly, mainly during July to October, and several storms year-round. According to the statistics suggested by Water Conservancy Agency of Ministry of Economic Affairs, annual lost due to typhoon includes about three thousands of houses damaged and one hundred and twenty-eight thousands millions collars of loss. This research has collected data relation to typhoons allotted among many agencies. By analyzing of cross-correlation between the data, the results show that the accumulative rainfall and scale of disaster depends on different paths of typhoon. According to statistics, each typhoon causes loses about 2 billion dollars including the loss of agriculture, fishery, human casualty, and building collapses, There is also an evidence to show when the amount of accumulative rainfall surpassed 200mm in Northern, 300mm in Midland, 350mm in Southern and 300mm in Eastern area of Taiwan, it will be increases the probability of flood to 40% in each regions. Besides, the all typhoons© which appear during fall, coming from the south of Taiwan are 60% of all. Those typhoons during fall no matter coming from the east cr west of Taiwan will certainly bring a great quantity of rainfall in Taiwan eastern area because of their counterclockwise rotation and the influence of northeast monsoon. Lastly. the northwest typhoon which passes through the north of Taiwan will make two obvious mass of rainfall in north and midst of Taiwan

Modeling Hydrological Impacts of Groundwater Level in the Context of Climate and Land Cover Change

The study uses weather generation models to generate future daily rainfall and temperature, and incorporates a land coverage model to simulate future land use changes. These future scenarios are then simulated by a rainfall runoff model to study their impacts on basin discharge, river, and groundwater levels. The Fengshan Creek basin in northern Taiwan is selected as test site. The RCP2.6 scenario is adopted to project future climate. The hydrological impacts, in the context of groundwater, for the near future (2020 - 2039), future (2050 - 2069), and distant future (2080 - 2099) are discussed. Simulations indicate that the influence of climate change is more important compared to local land cover changes at our study site. Both river stage and groundwater levels are influenced under future scenarios, but seasonally rather than annually; the dry and wet seasons are amplified. The results indicate that future water resources will be scarce in the dry season and more abundant in the wet season. In addition, changes in groundwater levels for mountainous region are more significant than in the downstream flat areas

Spatiotemporal Rainfall Distribution of Soan River Basin, Pothwar Region, Pakistan

This study evaluates the spatiotemporal rainfall variability over the semimountainous Soan River Basin (SRB) of sub-Himalayan Pothwar region, Pakistan. The temporal rainfall trend analysis of sixteen rain gauges was performed on annual basis with long-term (1981–2016) data. The results depicted that there is substantial year-to-year and season-to-season variability in rainfall patterns, and rainfall patterns are generally erratic in nature. The results highlight that most of the highland rainfall stations showed decreasing trends on annual basis. The central and lowland stations of the study area recorded an increasing trend of rainfall except for Talagang station. The average annual rainfall of the study area ranges between 492 mm and 1710 mm in lowland and high-altitude areas, respectively. Of the whole year’s rainfall, about 70 to 75% fall during the monsoon season. The rainfall spatial distribution maps obtained using the inverse distance weighting (IDW) method, through the GIS software, revealed the major rainfall range within the study area. There is a lack of water during postmonsoon months (November–February) and great differences in rainfall amounts between the mountainous areas and the lowlands. There is a need for the rational management of mountainous areas using mini and check dams to increase water production and stream regulation for lowland areas water availability. The spatiotemporal rainfall variability is crucial for better water resource management schemes in the study area of Pothwar region, Pakistan

Rainwater Harvesting Potential and Utilization for Artificial Recharge of Groundwater Using Recharge Wells

This study devised a practical solution to mitigate urban inundation and artificial recharge of groundwater using recharge wells which is the most viable surface runoff rainwater harvesting (RWH) technique in urban areas. The Rainwater Harvesting Pilot Project at Gaddafi Stadium Lahore was established to deal with urban flooding, artificial recharge of groundwater, and to avoid the mixing of rainwater in municipal sewerage. The study showed that Lahore city has great RWH potential from critical ponding roads that can be utilized to recharge the Lahore aquifer. With that ratio of recharge, the groundwater level can rise to 3.54 ft after every monsoon period if the same recharge wells structure are used, which is a key to groundwater sustainability in Lahore city. Moreover, the maximum recharging capacity of wells was 29.32 m3/h with satisfactory performance. Both recharge wells cleared the ponding volume within 3 to 3.5 h after the rainfall stopped. The filter media performance was also favorable with 25%–30% removal of contamination. All the water quality parameters were within the permissible limit against prescribed standards except coliform count that indicated the presence of sewage. In such a case the mixing of charcoal is recommended to shut up the coliform signals. This study identified that RWH using recharge wells is an alternative freshwater supply source for sustainable development of Lahore city and this technique should be the part of Master Planning and Policy Decision of Lahore as a suggestion

Improving AVSWAT Stream Flow Simulation by Incorporating Groundwater Recharge Prediction in the Upstream Lesti Watershed, East Java, Indonesia

The upstream Lesti watershed is one of the major watersheds of East Java in Indonesia, covering about 38093 hectares. Although there are enough water resources to meet current demands in the basin, many challenges including high spatial and temporal variability in precipitation from year to year exist. It is essential to understand how the climatic condition affects Lesti River stream flow in each sub basin. This study investigated the applicability of using the Soil and Water Assessment Tool (SWAT) with the incorporation of groundwater recharge prediction in stream flow simulation in the upstream Lesti watershed. Four observation wells in the upstream Lesti watershed were used to evaluate the seasonal and annual variations in the water level and estimate the groundwater recharge in the deep aquifer. The results show that annual water level rise was within the 2800 - 5700 mm range in 2007, 3900 - 4700 mm in 2008, 3200 - 5100 mm in 2009, and 2800 - 4600 mm in 2010. Based on the specific yield and the measured water level rise, the area-weighted groundwater predictions at the watershed outlet are 736, 820.9, 786.7, 306.4 mm in 2007, 2008, 2009, and 2010, respectively. The consistency test reveals that the R-square statistical value is greater than 0.7, and the DV (%) ranged from 32 - 55.3% in 2007 - 2010. Overall, the SWAT model performs better in the wet season flow simulation than the dry season. It is suggested that the SWAT model needs to be improved for stream flow simulation in tropical regions

Micro-Watershed Management for Erosion Control Using Soil and Water Conservation Structures and SWAT Modeling

This study evaluated the effectiveness of soil and water conservation structures for soil erosion control by applying a semi-distributed Soil and Water Assessment Tool (SWAT) model in various small watersheds of the Chakwal and Attock districts of Pothwar, Pakistan. The validated model without soil conservation structures was applied to various ungauged small watershed sites with soil conservation stone structures. The stone bund-type structure intervention was used in the model through the modification of the Universal Soil Loss Equation (USLE) to support the practice factor (P-factor), the curve number, and the average slope length for the sub-basin (SLSUBBSN). The structures had significant effects, and the average sediment yield reduction caused by the soil conservation stone structures at these sites varied from 40% to 90%. The sediment yield and erosion reductions were also compared under conditions involving vegetation cover change. Agricultural land with winter wheat crops had a higher sediment yield than fallow land with crop residue. The fallow land facilitated sediment yield reduction, along with soil conservation structures. The slope classification analysis indicated that 60% of the agricultural area of the Chakwal and Attock districts lie in a slope range of 0–4%, where considerable potential exists for implementing soil conservation measures by installing soil conservation stone structures. The slope analysis measured the suitability of conservation structures in the semi-mountainous Pothwar area in accordance with agriculture practice on land having a slope of less than 5%. The SWAT model provides reliable performance for erosion control and watershed management in soil erosion-prone areas with steep slopes and heavy rainfall. These findings can serve as references for policymakers and planners

Modeling of Mixed Crop Field Water Demand and a Smart Irrigation System

Taiwan average annual rainfall is approximately 2500 mm. In particular, 80% of the rainfall occurs in summer, and most of the heavy rainfall is caused by typhoons. The situation is worsening as climate change results in uneven rainfall, both in spatial and temporal terms. Moreover, climate change has resulted the variations in the seasonal rainfall pattern of Taiwan, thereby aggravating the problem of drought and flooding. The irrigation water distribution system is mostly manually operated, which produces difficulty with regard to the accurate calculation of conveyance losses of channels and fields. Therefore, making agricultural water usage more efficient in the fields and increasing operational accuracy by using modern irrigation systems can ensure appropriate irrigation and sufficient yield during droughts. If agricultural water, which accounts for 70% of the nation’s total water usage, can be allocated more precisely and efficiently, it can improve the efficacy of water resource allocation. In this study, a system dynamic model was used to establish an irrigation water management model for a companion and intercropping field in Central Taiwan. Rainfall and irrigation water were considered for the water supply, and the model simulated two scenarios by reducing 30% and 50% of the planned irrigation water in year 2015. Results indicated that the field storage in the end block of the study area was lower than the wilting point under the 50% reduced irrigation water scenario. The original irrigation plan can be reduced to be more efficient in water usage, and a 50% reduction of irrigation can be applied as a solution of water shortage when drought occurs. However, every block should be irrigated in rotation, by adjusting all water gates more frequently to ensure that the downstream blocks can receive the allocated water to get through the drought event