{{refimprove|date=April 2025}} {{Infobox river | name = Grindulu River | name_other = | image = | image_caption = | pushpin_map = Indonesia Java#Indonesia | pushpin_map_caption = <!---------------------- LOCATION --> | subdivision_type1 = Country | subdivision_name1 = [[Indonesia]] | subdivision_type2 = Provinces | subdivision_name2 = [[East Java]] <!---------------------- PHYSICAL CHARACTERISTICS --> | source1 = [[Mount Gembes]] | source1_location = [[Bandar, Pacitan|Bandar]], [[Pacitan Regency|Pacitan]] | source1_elevation = {{cvt|1200|m}} | source2 = Berkala River (-8.07083, 111.3125) | source2_location = [[Tegalombo, Pacitan|Tegalombo]], [[Pacitan Regency|Pacitan]] | source2_elevation = {{cvt|232|m}} | mouth = [[Teluk Pacitan]], [[Samudra Hindia]] | mouth_location = [[Ploso, Pacitan|Ploso]], [[Pacitan Regency|Pacitan]] | mouth_coordinates = {{coord|-8.2338|111.1039|format=dms|type:river_region:ID|display=inline,title}} | length = {{convert|70|km|mi|abbr=on}} | basin_size = {{Convert|715|km2|mi2|abbr=on}}<ref name="Lampiran Peraturan Menteri Kehutanan 511-2011">https://hukumonline.com/pusatdata/detail/lt4f2f760d2fff3/keputusan-menteri-kehutanan-nomor-sk511menhutv2011-tahun-2011</ref> <!---------------------- BASIN FEATURES --> | river_system = DAS Grindulu (DAS230561)<ref name="Lampiran Peraturan Menteri Kehutanan 511-2011">https://hukumonline.com/pusatdata/detail/lt4f2f760d2fff3/keputusan-menteri-kehutanan-nomor-sk511menhutv2011-tahun-2011</ref> | custom_label = River management | custom_data = BPDAS Solo<ref name="Lampiran Peraturan Menteri Kehutanan 511-2011">https://hukumonline.com/pusatdata/detail/lt4f2f760d2fff3/keputusan-menteri-kehutanan-nomor-sk511menhutv2011-tahun-2011</ref> }}
The '''Grindulu River''' is a river in [[East Java]], Java, Indonesia. It flows from [[Mount Gembes]] (1,200 [[metres above sea level]]), [[Pacitan Regency|Pacitan Recency]], at the border of [[Jeruk Village]] and [[Bangunsari Village]] in the [[Bandar District]]. It then flows through the [[Tegalombo District]] and the [[Arjosari District]] in the [[Pacitan Regency]], and into the [[Indian Ocean]] at [[Ploso Village]]. Grindulu River is approximately 70 km long, flowing from the northeast to the southwest before turning south.
== Hydrology == The Grindulu [[river basin]] stretches through three regencies: the [[Pacitan Regency]], the [[Ponorogo Regency]], and the [[Wonogiri Regency]]. The basin covers an area of approximately 655,40 km<sup>2</sup>. 593,8 km<sup>2</sup> of the river basin (90.6%) is in the Pacitan Regency.<ref name="tukul">{{Cite web |title=Bendungan Tukul |url=https://kppip.go.id/proyek-strategis-nasional/bendungan-dan-irigasi/bendungan-tukul/ |access-date=2025-04-25 |website=Komite Percepatan Penyediaan Infrastruktur Prioritas}}</ref>
=== Tributary === Major tributaries include:
* [[Jelok River]] * [[Ponggok River]] * [[Siru River]] * [[Asemgondok River]] * [[Tengi River]] * [[Ngepoh River]] * [[Ngreco River]] * [[Jaten River]] * [[Plaosan River]] * [[Sungmantung River]] * [[Gemaharjo River]] * [[Kapa River]] * [[Ploso River]] * [[Dungdowo River]] * [[Jati River]] * [[Pasan River]] * [[Ngaglik River]] * [[Pelemsengir River]]
== Geomorphology == The Grindulu watershed is primarily affected by local residents' control of dry land, which impacts the development of the surface soil conditions of the Grindulu watershed. Soil makes up 61.29% of the area around the river, with very thin [[solum]] and [[Orthent|lithosol]] parent rock outcrops. This highly erosive topsoil layer impacts the high levels of sedimentation around the river.
Erosion levels around the Gindulu River watershed are very high, with at least 60 tons of soil per hectare transported annually. Erosion levels are calculated by measuring variables like soil characteristics, land use patterns, land management, and topographic conditions.
In addition to surface flow, the Gindulu River flows underground within the [[Pringkulu District]] and [[Donorojo District]]. The underground river flows through a complex system of cave passages and underground channels, resulting in limestone ([[karst]]) reef facies. The discharge from the underground river reaches 176.70 litres/second.<ref name="tukul"/>
== Geography == The Gindulu River flows in the south-central region of Java, which typically has a tropical monsoon climate. The average annual temperature is around 23°C, with a high of 26°C in October and a low of 20°C in April.<ref name="nasa">{{Cite web |date=30 January 2016 |title=NASA Earth Observations Data Set Index |url=http://neo.sci.gsfc.nasa.gov/dataset_index.php |url-status=dead |archive-url=https://web.archive.org/web/20200510015442/ |archive-date=2020-05-10 |access-date=2018-12-04 |website=NASA Earth Observations |publisher=NASA}}</ref>
The average annual rainfall is 2703 mm. Monthly rainfall reaches a high of 477 mm in January and a low of 29 mm in August.<ref name="nasarain">{{Cite web |date=30 January 2016 |title=NASA Earth Observations: Rainfall (1 month - TRMM) |url=http://neo.sci.gsfc.nasa.gov/view.php?datasetId=TRMM_3B43M&year=2014 |url-status=dead |archive-url=https://web.archive.org/web/20190419091014/https://neo.sci.gsfc.nasa.gov/view.php?datasetId=TRMM_3B43M&year=2014 |archive-date=2019-04-19 |access-date=2018-12-04 |website=NASA Earth Observations |publisher=NASA/Tropical Rainfall Monitoring Mission}}</ref>{{Climate chart|Grindulu River|19|24|477|22|24|331|20|23|322|18|22|212|21|25|172|20|26|189|20|25|132|20|25|29|20|27|44|21|30|89|20|27|258|22|24|447}}
== Utilization == The Grindulu River watershed area contains many natural resources, such as stones, sand and various types of fish. Residents along the Grindulu River utilize the river for agricultural and fishery (through traditional fishing and netting). The large water discharge of the Grindulu River is also used for traditional irrigation.
The Tukul Reservoir Dam is currently under construction on the [[Asemgondok River]], next to the [[Karanggede Village]] in the [[Arjosari District]]. The dam has a planned capacity of 8.68M³ and is expected to irrigate 600 hectares of land and provide raw water supply at 0.35M³/second, generating 0.64 MW of electricity.<ref name="tukul"/>
== References == {{Reflist}}
{{Rivers of East Java}}
[[Category:Rivers of East Java]]