A reservoir is one of the water resource utilizations that functions as storage and provider of water, both as raw material for clean water and irrigation. Gondang Reservoir in Lamongan Regency Indonesia is a reservoir that provides water supply to 7 field reservoirs for 10 months covering an area of 6,233 ha, especially during the dry season. The Corong watershed is a watershed that flows through the Gondang reservoir. If there is a water deficit due to drought in the Corong watershed, the impact will be large for the Gondang irrigation area. Therefore, it is necessary to monitor drought in the Corong watershed. This study aimed to model and forecast the meteorological drought, represented by the Standardized Precipitation Evapotranspiration Index (SPEI) using Seasonal Autoregressive Integrated Moving Average (SARIMA). Forecasting error was evaluated using Mean Square Error (MSE). The intensity, frequency, and trend of droughts were analyzed using SPEI with a time range of 1-,3-,6-, and 12 using Rstudio. The results of the worst drought index were analyzed using the SPEI method in the 1-month worst drought in August 2003, the 3-month deficit period in February 2007, the 6-month deficit period in March 2007, and the 12-month in March 2007. The SARIMA Model (3,0,0) (2,1,0) 48 was convenient to be used for forecasting Drought index SPEI-1 in the Corong river basin area because the estimation of each of the parameters was significantly different from zero, fulfilling the diagnostic test in which the residuals from the model were random and normally distributed, and had mean squared value of 1,052. The result showed that meteorological drought was related to hydrological drought and had the potential to be affected by drought. Thus, droughts need to be prioritized in disaster mitigation.

Concrete is a composite material (mixture) of several materials, whose main material consists of a mixture of cement, fine aggregates, coarse aggregates, water and or without other added ingredients coconut fibers are only used for broom materials, rugs, ropes and household appliances.Therefore, the addition of burning concrete into coconut ash ash is tried.The method used was experimental carried out in the laboratory with the production of 12 test pieces with presentations of 0%, 0.25%, 0.5% and 0.75% at 7 days.Laboratory test results on the addition of coconut fiber ash to the normal K 100 presentation were 16.505 MPa, coconut fiber ash mixture 0.25% reached 23.895 MPa, coconut fiber ash mixture 0.5% reached 23.656 MPa, the highest fiber ash mixture concrete 0.75% coconut can reach compressive strength of 23,688 MPa.

Drought trends are occurring throughout Indonesia, including in Lamongan Regency. The problems caused by drought significantly affect the agricultural sector in Lamongan, with varying impacts each year. This study uses the Normalized Difference Vegetation Index (NDVI) method integrated with Geographic Information Systems (GIS) to monitor and analyze vegetation conditions as an indicator of drought. Based on the Landsat 8 imagery analysis from August to October 2019-2021, the results show significant changes in vegetation conditions related to drought. The year 2020 showed a decrease in areas with high greenness, while 2021 showed a significant recovery. This vegetation monitoring is expected to serve as a basis for more effective drought mitigation policies for the agricultural sector in Lamongan Regency.

This research explores the relationship between hydrological drought and agricultural drought in the Corong River Basin, focusing on the Gondang Reservoir Irrigation Area, Indonesia. By employing a Causal Time Series Regression Model, the study uncovers that agricultural drought twelve months prior has a significant impact on current agricultural drought and is influenced by current hydrological drought. Time series regression analysis reveals that 45.86% of agricultural drought is influenced by hydrological drought, with 54.14% influenced by other factors besides rainfall. Further research is needed to investigate these additional factors. These findings have practical implications, serving as a valuable index for assessing drought severity and planning mitigation actions, especially in the irrigation areas of interest. They emphasize the importance of effective irrigation management, appropriate cropping patterns, and a comprehensive understanding of the complex characteristics of drought in agricultural regions through comprehensive monitoring efforts in agricultural drought mitigation.