Identification of Spring Distribution in the Pusur Sub-Watershed and Surroundings Using Geographic Information System

. Groundwater is the water that originates from the surface and infiltrates the ground, forming a hydrological system. The presence of groundwater is influenced by various factors, including climate conditions, geomorphology, geology, human activities, and land cover conditions. The Pusur Sub-Watershed area is part of the Bengawan Solo Watershed, and it is known to have a distribution of spring sources with varying levels of productivity. The presence of spring sources provides benefits for fulfilling needs in various sectors of life. This study aims to identify the distribution of springs and the productivity levels of aquifers in the Pusur Sub-Watershed area. The method used involves conducting surveys and ground checks of spring locations in the Pusur Sub-Watershed area. Subsequently, the spring distribution information is overlaid with a hydrogeological map. The results of the analysis indicate that the aquifer productivity in the Pusur Sub-Watershed area is divided into five categories: moderate productivity, moderate-localized productivity, high productivity, widespread productivity, and localized-localized productivity. The highest concentration of springs is found in the Polanharjo, Tulung, and Jatinom Districts, categorized as high productivity. Meanwhile, in the Musuk and Tamansari Districts, sprin † gs are also found in the localized-localized productivity category


Introduction
One of the basic human needs is water.The availability of high-quality water that meets the standards, in abundant quantity (quantity), and consistently over time is essential.The utilization and increasing demand for water resources, in line with population growth and economic development, undoubtedly affect the balance of groundwater.Given this, it is only appropriate that environmentally sustainable water resource management efforts be carried out.
Groundwater is a component of a continuous hydrological cycle that occurs naturally.Asdak (2010) states that in this process of water circulation, the volume of groundwater constantly undergoes changes in recharge and discharge.The processes of water recharge and discharge come from rainfall infiltration, surface water bodies, and artificial reservoirs.The infiltration of water below the soil surface can be either saturated or unsaturated.A saturated groundwater system is groundwater within a rock layer in an Aquifer Basin (CAT) (Sadjab et al., 2012).CATs are generally delimited by boundaries influenced by geological and hydrogeological conditions (Zeffitni, 2011).Areas with groundwater potential are typically unconfined deposits * Corresponding author: dd11lb@yahoo.comthat can release water that is thousands of years old (Riastika, 2012).
An aquifer is a groundwater-bearing layer that plays a crucial role in meeting the water needs of living organisms (Sulu et al., 2015).According to Jone (2018), in his research, the development of an area affects the presence of groundwater and the groundwater cycle.The availability of groundwater is influenced by the geological conditions in each area.These characteristics affect the values of porosity and permeability in the composition of aquifer rock.
Pusur Sub-Watershed AS (And Surrounding) region has three areas: upstream, middle, and downstream.In his research, Asdak (2014) states that the classification of watershed areas has distinct characteristics that differ from one another.The upstream area has the characteristic of being a water recharge area, the middle area serves as a water distributor that stores water from the upstream and then releases it in that area.The upstream area of Sub-DAS Pusur is located in Musuk Sub-District, the middle part is in Tulung and Polanharjo Sub-Districts, while the downstream area is in Delanggu and Juwiring Sub-Districts (BPDAS, 2016).GIS provides a transformation of spatial data into decision-making outputs.The combination of geographic analysis supports the preferences of decision-makers (Malczewski, 2004).Several studies have mentioned that the use of GIS helps in locating groundwater recharge areas (Devianto et al., 2017).
To date, the distribution of springs in Pusur Sub-Watershed AS has not been well-mapped, while the need for information on spring distribution and aquifer productivity is essential.This study aims to determine the distribution of springs and the level of aquifer productivity in Pusur Sub-Watershed DAS.

Methodology 2.1 Time and Place
The research was conducted in December 2022 in Boyolali and Klaten Regencies, Central Java.The study area covered the Pusur Sub-watershed, Dengkeng Subwatershed, and Bambang Sub-watershed.

Material and Tools
The materials used included spring distribution data obtained from direct field measurements and data from administration records downloaded from https://tanahair.indonesia.go.id/portalweb/downloadpet acetak.Additionally, aquifer maps used were digitized on-screen from aquifer productivity publications by the Ministry of Energy and Mineral Resources (ESDM).The software utilized for this research included spreadsheet software and ArcGIS.In general, the rock formation in the Sub-district of Pusur and its surrounding areas (Sub-districts of Dengkeng and Bambang) is predominantly composed of the Young Mount Merapi formation.The Young Mount Merapi formation is a major aquifer with good permeability, resulting in the emergence of numerous springs in the region.These springs typically form a pattern resembling a belt, referred to as a spring belt.According to Santosa's research ( 2006), spring belts tend to appear along the break of slope on the slopes and foothills of volcanoes.The pattern of these spring belts is influenced by geological factors related to the composition of the materials in the area and geomorphological factors that facilitate the emergence of springs (Ashari, 2014).
The average annual rainfall in the upstream region for the period 1981-2020 is approximately 2,581 mm/year.The upstream area, which includes the Tamansari District located on the peak and slopes of Mount Merapi, experiences higher rainfall compared to the central and downstream regions.Consequently, this area is of great importance as a recharge area, requiring conservative land resource management.Based on the Schmidt and Ferguson climate system analysis, Tamansari District, situated in the upstream region, has a type B climate, as does the central region, while the downstream region falls under the C climate type.Observing the distribution of average monthly rainfall in the form of a "V" pattern, it can be said that the entire Sub-district of Pusur AS is influenced by monsoonal winds.
Land use in the Sub-district of Pusur AS is predominantly characterized by paddy fields covering 41,455.43hectares in the central and downstream areas.Additionally, mixed dryland agriculture covers 12,491.43hectares, and dryland agriculture covers 8,024.35hectares in the upstream region.This is supported by Anggana's research (2022), which indicates that the upstream region is dominated by dryland agriculture, while the central and downstream regions are dominated by irrigated agriculture.
Sub-district Pusur And Surrounding covers an area of 88,435.67hectares and includes the Pusur Sub-watershed, Babang Sub-watershed, and Dengkeng Subwatershed, all of which are part of the upstream area of the Bengawan Solo River Basin.These three subwatersheds originate on the southeastern side of the Mount Merapi's topography.However, the upstream area of the Pusur Sub-watershed is limited to the base and does not extend to the slopes and peak of Mount Merapi, unlike the Babang and Dengkeng Subwatersheds, as indicated by Arnis et al.'s study (2017).The disparity between the abundant and extensive surface water and the relatively narrow catchment area of the Pusur Sub-watershed requires an examination of the relevance between surface water resources and groundwater resources.The spatial exploration study scope of water resource management is expanded not only to the Pusur Sub-watershed but also to the surrounding catchment areas, namely the Babang and Dengkeng Sub-watersheds, in an effort to establish coherence.This expanded study area is referred to as Sub-district Pusur AS (Figure 3).Nevertheless, the primary focus of this study is within the territorial scope of Sub-district Pusur DS.
In terms of administrative governance, Sub-district Pusur AS spans three administrative regions, with the upstream part of the Bengawan Solo River Basin falling within Boyolali Regency, the dominant central and downstream areas in Klaten Regency, and a small portion in Sukoharjo Regency.There are 63 villages spread across 9 sub-districts within the Pusur Subwatershed.Fifteen of these villages are entirely located within the Pusur Sub-watershed, including Pagerjurang Village, which is situated in the upstream part of the Pusur Sub-watershed.The names of these villages, their positions within the Pusur Sub-watershed, and their land areas are presented in Table 1.Water Resources in the Pusur AS constitute an integrated system of surface water and groundwater.Rainwater falling on the surface of the Sub-district of Pusur DS can either flow directly as runoff into the Pusur River system or infiltrate into the ground through the unsaturated (vadous zones) and saturated (Hadian, Mardiana, Abdurahman, & Iman, 2006) groundwater systems.The saturated groundwater system exists within a layer of rock in an aquifer that is part of the Karanganyar-Boyolali groundwater basin (covering an area of 3,877 km2), as per Regulation No. 2/2017 issued by the Ministry of Energy and Mineral Resources.The volcanic activity of Mount Merapi has shaped unique characteristics and potential within its morphology.According to Santosa & Sutikno (2006), the morphology of Mount Merapi comprises five units: the mountain peak, mountain slope, mountain foothill, mountain foothill plain, and volcanic fluvial plain.
Aquifers within the expanse of Mount Merapi follow its volcanic morphology, forming aquifer belts.In the mountain slope morphology unit at elevations of 250-500 meters above sea level (meters above sea level), there are high-productivity aquifer belts, while in the mountain foothill morphology at around 200 meters above sea level, high-productivity aquifers are also present.Numerous high-potential springs are scattered throughout the Sub-district of Pusur DS, originating from high-productivity aquifers, especially at elevations around 200 meters above sea level.

Potential and Utilization of Springs
The productivity of aquifers in the Pusur AS is divided into five categories: locally productive aquifers (2,777.88ha), widely spread productive aquifers (34,581.88ha), high-productivity aquifers (11,202.93 ha), moderately productive aquifers in local areas (19,221.1 ha), and moderately productive aquifers (20,651.88ha).
The analysis results indicate that aquifer productivity in the Sub-district of Pusur DS falls into five categories: moderate productivity, locally moderate productivity, high productivity, widely spread productivity, and locally spread productivity.The majority of springs are found in the areas of Polanharjo, Tulung, Jatinom, and Karangnongko in the high productivity category.Meanwhile, the areas of Musuk and Tamansari also have springs falling into the locally spread productivity category, with smaller discharge compared to the locations below them.https://doi.org/10.1051/e3sconf/202346808007ICST UGM 2023 The emergence of springs in volcanic areas is primarily due to geological forces from within the Earth, as non-gravitational springs.The Merapi region consists of volcanic rock formations and is abundant in springs.In Quaternary-aged areas, loose materials resulting from volcanic eruptions, such as sand and gravel, may contain pressurized groundwater, leading to the abundant emergence of springs on the surface.The Merapi slope region consists of various types of rocks within specific formations, potentially resulting in variations in spring discharge in some locations.
Based on field Groundcheck results, there are 38 springs utilized to meet various needs, including household water supply, tourism, fisheries, livestock farming, and agriculture.The majority of these springs are found in the Tulung and Polanharjo sub-districts of Klaten Regency.These locations align with the overlay of high aquifer productivity on the map.Mount Merapi, being an Old Stratovolcano, holds a high potential for springs, typically forming a belt-like pattern around its body known as a spring belt, resulting from changes in the rock structure (Purbohadiwidjojo, 1967).In the upstream areas, only three springs are found falling into the moderately productive category (Figure 4.).

Figure 1 .
Figure 1.Administrative Map of Pusur And Surrounding

Figure 2 .
Figure 2. Framework for Identifying Springs and Aquifers

Figure 4 .
Figure 4. Distribution of springs and aquifers with various productivity in the Pusur DAS 3.3 Conclusion a) The productivity of aquifers in the Sub-district of Pusur AS is categorized into five groups: locally productive aquifers (2,777.88ha), widely spread productive aquifers (34,581.88ha), highproductivity aquifers (11,202.93 ha), locally moderately productive aquifers (19,221.1 ha), and moderately productive aquifers (20,651.88ha).b) Land use in the Sub-district of Pusur AS is divided into nine categories, including Secondary Dryland Forest, Tree Plantations, Open Land, Settlements, Dryland Agriculture, Mixed Dryland Agriculture, Rice Fields, Mining, and Plantations.The dominant land use is paddy fields, covering 41,455.43hectares in the central and downstream areas.Additionally, mixed dryland agriculture covers 12,491.43hectares, and dryland agriculture covers 8,024.35hectares in the upstream region.c) Based on the field Groundcheck results, there are 38 springs utilized to meet various needs, including household water supply, tourism,
Description: *Villages that have 100% of the area within the Pusur sub-watershed