Chapter 6. Payments for groundwater recharge to ensure groundwater supply in Kumamoto, Japan1

This chapter discusses the case of Kumamoto, Japan, which provides an illustration of a payment for ecosystem services scheme to provide financial incentives for groundwater recharge. The case documents how the scheme managed to raise groundwater levels, improving the security of supply for industrial and other groundwater users.


Groundwater depletion and declining recharge in Kumamoto, Japan

Kumamoto2 is well known for its groundwater abundance and quality. The region is located in the centre of Kyushu, the southern major island of Japan. Kumamoto City, with a population of 730 000, is also the largest Japanese city that provides 100% of its drinking water from groundwater (UNDESA, 2016). Groundwater is also an essential source of water for agriculture and industry in the region (UNESCO et al., 2015).

Kumamoto City is located in the lower part of an aquifer that is recharged by inflow from the Shirakawa River. The surface layer of the aquifer in Kumamoto has a particularly high permeability and groundwater recharge capacity.3 Today, one third of groundwater recharge in the region is due to the irrigation of paddy fields with water diverted from the Shirakawa River. Rice paddies in the mid-basin of the river can recharge 5-10 times as much as those in other regions of the country (Nishimiya, 2010). Every kilogramme of rice produced in this area is estimated to raise groundwater levels by approximately 20-30 m3 (UNDESA, 2016).

Despite the exceptionally high recharge capacity of the aquifer, the groundwater level has declined over recent decades and the recharge capacity of the Shirakawa River is forecasted to decline by 6.2% between 2007 and 2024 (Gundimeda and Wätzold, 2010). This decline is due mainly to a government policy to reduce rice production acreage, which has forced farmers to abandon their paddy fields (UNESCO et al., 2015; UNDESA, 2016). The rice acreage-reduction policy, which was introduced in the 1970s, is a supply-restriction arrangement aimed at supporting prices. Approximately 40% of Japan’s paddy fields are subject to acreage-reduction (Kazuhito, 2008).4 The rice reduction policy has resulted in a significant decrease in agricultural irrigation in Kumamoto with a resulting decline in groundwater recharge (UNDESA, 2016; UNESCO et al., 2015).

The decline in groundwater levels is also a result of increased pumping, as well as rapid urbanisation. An increase in asphalt and concrete surfaces has weakened the ground’s capability to absorb water, hence to recharge groundwater (UNDESA, 2016; UNESCO et al., 2015; MoE, 2010). Urbanisation has also led many farmers to abandon rice production, thus further impacting the level of groundwater recharge (ICLEI, 2013).

Promoting groundwater recharge through payments for ecosystem services

To reverse groundwater depletion, a programme for payment for ecosystem services (namely, groundwater recharge) was launched in 2003 as a result of direct negotiations between local farmers and the Kumamoto Technology Centre (Kumamoto TEC), a subsidiary of Sony Semiconductor Kyushu (Hayashi and Nishimiya, 2010). Kumamoto TEC aimed to promote the recharge of the large volumes of groundwater consumed by its semiconductor plant with the objective of becoming “water neutral” (MoE and KC, 2016). The PES scheme allowed the company to pay farmers (per square kilometre per 30 days of flooding) to recharge groundwater by voluntarily flooding fields that had been converted from irrigated rice fields to crop fields. This was be done with water from the Shirakawa River during fallow periods (MoE and KC, 2016; UNESCO et al., 2015; Hayashi and Nishimiya, 2010).

Kumamoto’s city government joined the PES programme in 2004 and took a number of complementary actions to encourage groundwater conservation (MoE and KC, 2016). They re-named the PES scheme “Project to Flood” and included it as part of its Water Conservation Plan running from 2004 to 2009 and renewed for the period 2009-13 (Hayashi and Nishimiya, 2010). In parallel, the city government revised the Groundwater Preservation Ordinance, which declared groundwater as a common good that should be conserved (UNESCO et al., 2015). The city also signed a ten year agreement with neighbouring towns, ensuring cross-municipal co-operation for groundwater conservation. The agreement involved the expansion of Project to Flood and the protection of watershed forest in the upper Shirakawa Basin (UNDESA, 2016).

The programme has since expanded, with the Council for Sustainable Water Use in Agriculture5 (CSWUA) taking on the task of ensuring that flooding is being carried out (UNDESA, 2016; Hayashi and Nishimiya, 2010). Furthermore, several other private companies have committed to fund the recharge programme together with the local authorities. In general, the primary motivation of companies to join the Project to Flood is their interest in preventing groundwater depletion so as to secure sufficient amounts of groundwater for their business activities in the future (MoE and KC, 2016).

The city government and the private companies that have committed to the Project to Flood provide farmers with payment in exchange of their contribution to groundwater recharge. The level of payment is calculated based on an estimate of the preparation and management costs of flooding (Hayashi and Nishimiya, 2010). The CSWUA distributes the payments to farmers (MoE and KC, 2016; UNESCO et al., 2015). In order to receive payments for flooding, farmers have to be located in Kumamoto or in one of the neighbouring municipalities (Ozu-Machi or Kikuyo), use water from the Shirakawa River for irrigation, carry out the flooding for one to three months between May and October before or after cultivation of crops (Kumamoto Water Life, n.d.).

Project to Flood6 has also inspired related initiatives, including a voluntary scheme to encourage organic rice production. Launched by an agricultural cooperative in Kumamoto in partnership with the city government, the initiative encourages rice cultivation with reduced fertiliser and pesticide use in the fields flooded under Project to Flood. It is supported by local companies, universities and consumers, who buy the “eco-rice” at a slightly higher price than conventional rice (MoE, 2016).

An increase in groundwater recharge

The PES programme in Kumamoto has contributed to increasing groundwater recharge. Figure 6.1. illustrates how groundwater recharge supported by the programme has exceeded water consumption at Kumamoto TEC in most years. In addition to recharging groundwater, the flooding helps limit the negative impact of diseases, weeds and insects (Nishimiya, 2010, UNDESA, 2016).

Figure 6.1. Groundwater recharge has exceeded water consumption at Kumamoto TEC, 2003-15

Note: No data available for 2010 and 2011.

Source: Author, based on data from Sony Semiconductor Corporation (2016) Notes: No data available for 2010 and 2011.

In 2013, Project to Flood was recognised as the year’s best practice in water management by the United Nations Water Decade Programme on Advocacy and Communication and the UN World Water Assessment Programme (UNDESA, 2016; ICLEI, 2013). Kumamoto City’s first ten year agreement on the implementation of Project to Flood was completed in 2013, and a second ten year agreement has been initiated. The local government has signalled its interest in continuing the project thereafter (MoE and KC, 2016).

Lessons learned

The case of Kumamoto is one of several examples of cities taking innovative action towards groundwater conservation (OECD, 2015). The case illustrates how a payment for ecosystem services scheme can reverse the groundwater depletion. It also illustrates the importance of policy coherence across agricultural, urban and water policies (see Health Check #10, Part I).

Initially launched by the private sector in partnership with farmers, the scheme later expanded to include local government. The integration of the PES scheme into the local government’s broader groundwater management policies has allowed for a more sustained response as well as broader collaboration with an increased number of stakeholders from the public and private sectors as well as civil society. The stakeholders demonstrated a solid understanding of the availability of groundwater resources in the area, the challenges associated with depletion and the possibility to augment supplies through recharge (see Health Check #3, Part I). The programme has facilitated the restoration of groundwater levels and demonstrates how such schemes can provide effective incentives for groundwater recharge while providing greater security of supply for groundwater users.


Gundimeda, H. and F. Wätzold (2010), “Payments for ecosystem services and conservation banking”, In TEEB, The Economics of Ecosystems and Biodiversity for Local and Regional Policy Makers, www.teebweb. org/media/2010/09/TEEB_D2_Local_Policy-Makers_Report-Eng.pdf.

Hayashi, K. and H. Nishimiya (2010), “Good practices of payments for ecosystem services in Japan”, EcoTopia Science Institute Hayashi Laboratory Policy Brief, No. 1, Nagoya, Japan,

ICLEI (2013), “Kumamoto’s ’Project to flood’ wins UN-Water Award”, (accessed 7 July 2016).

Kazuhito, Y. (2008), “The pros and cons of Japan’s rice acreage-reduction policy”, The Tokyo Foundation,

Kumamoto Water Life (n.d.), “Groundwater protection”, asp?c_id=25&id=9&mst=0&type (accessed 18 July 2016).

Ministry of the Environment, Japan (MoE) (2010), “Payment for ecosystem services: Best practices from Japan: Conserving water by recharging groundwater in Kumamoto”, (accessed 7 July 2016).

Ministry of Environment in Japan and Kumamoto City authorities (MoE and KC) (2016), personal correspondence.

Nishimiya, N. (2010), “Offsetting industrial groundwater consumption through partnerships between industry and farmers”, The Economics of Ecosystems and Biodiversity, partnerships%20between%20industry%20and%20farmers.pdf (accessed 21 July 2016).

OECD (2015), Water and Cities: Ensuring Sustainable Futures, OECD Studies onWater, OECD Publishing, Paris,

Sony Semiconductor Corporation (2016), “Feature: Working on Groundwater Recharge Projects”, (accessed 18 February 2017).

UNDESA (2016), “Basin wide groundwater management using the system of nature: Kumamoto city, Japan”, Water for Life, UN-Water Best Practices Award 2013 edition: Winners, decade/winners2013.shtml (accessed 2 September 2016).

UNESCO et al. (2015), “Global Diagnostic on Groundwater Governance”, UNESCO, the International Hydrological Programme, the World Bank, the Food and Agriculture Organisation, the Global Environment Facility and the International Organisation of Hydrogeologists, www.groundwater


← 1. This document and any map included herein are without prejudice to the status of or sovereignty over any territory, to the delimitation of international frontiers and boundaries and to the name of any territory, city or area.

← 2. Kumamoto is both the name of a city and a region.

← 3. This is due to geographic features of the aquifer as well as the establishment of paddy fields more than 400 years ago (UNDESA, 2016).

← 4. Approximately 40% of Japan’s paddy fields are subject to acreage-reduction (Kazuhito, 2008).

← 5. The CSWUA consists of local municipalities, land improvement districts and agricultural co‐operatives.

← 6. Project to Flood also involves awareness raising programmes, and since 2008, local governments designate three "Water Saving Months" per year. During these months, daily water consumption per capita is publicly reported and water saving devices are promoted (ICLEI, 2013).