The Assessment of Hydrological Availability and the Payment for Ecosystem Services: A Pilot Study in a Brazilian Headwater Catchment

Abstract

The assessment of water availability in river basins is at the top of the water security agenda. Historically, the assessment of stream flow discharge in Brazilian watersheds was relevant for dam dimensioning, flood control projects and irrigation systems. Nowadays, it plays an important role in the creation of sustainable management plans at the catchment scale aimed to help in establishing legal policies on water resources management and water security laws, namely, those related to the payment for environmental services related to clean water production. Headwater catchments are preferential targets of these policies and laws for their water quality. The general objective of this study was to evaluate water availability in first-order sub-basins of a Brazilian headwater catchment. The specific objectives were: (1) to assess the stream flow discharge of first-order headwater sub-basins and rank them accordingly; (2) to analyze the feasibility of payment for environmental services related to water production in these sub-basins. The discharge flow measurements were conducted during five years (2012 to 2016), in headwaters in a watershed on the São Domingos River at the Turvo/Grande Watershed, represented as the 4th-largest hydrographic unit for water resources management—UGRHI-15 in São Paulo State, Brazil. A doppler velocity technology was used to remotely measure open-channel flow and to collect the data. The discharge values were obtained on periodic measurements, at the beginning of each month. The results were subject to descriptive statistics that analyzed the temporal and spatial data related to sub-basins morphometric characteristics. The discharge flows showed space–time variations in magnitude between studied headwater sub-basins on water availability, assessed based on average net discharges. The set of ecological processes supported by forests are fundamental in controlling and recharging aquifers and preserving the volume of water in headwater in each sub-basin. The upstream inflows influence downstream sub-basins. To avoid scarcity, the headwater rivers located in the upstream sub-basins must not consider basin area as a single and homogeneous unit, because that may be the source of water conflicts. Understanding this relationship in response to conservationist practices installed uphill influenced by anthropic actions is crucial for water security assessment. The headwaters should be considered a great potential for ecosystem services, with respect to the “provider-receiver” principle, in the context of payments for environmental services (PES).

Airsheds, watersheds and more – The flows that drive intra-extra-urban connections, and their implications for nature-based solutions (NBS)

“…Taking a wider 'sheds' approach, upstream catchment management can be used to mitigate flooding in cities to some extent, using NBS instead of, or to supplement, dams and hard flood defences. Levers to achieve this, such as payments for ecosystem services, can incentivise land management practices which reduce downstream flood risk or improve water supply and quality [48][49][50]. Natural Flood Management activity such as restoring peatlands, river channels and floodplains, establishment of woodland, and encouraging natural waterlogging to detain runoff can reduce the height or timings of flood peaks in downstream cities [51,52], but may not mitigate the highest flow events [53].…”

Small tradeoffs between social equity and conservation outcomes in a freshwater payment for ecosystem services scheme

“…Despite PES programs in freshwater ecosystems being the most widespread by geographical distribution and transaction value (Salzman et al, 2018), terrestrial and marine ecosystems have received the most attention, particularly in the context of protected areas implementation (Dawson et al, 2018; Schreckenberg et al, 2016; Zafra‐Calvo et al, 2017), REDD+ evaluation (Börner et al, 2020; Brimont et al, 2015; Pascual et al, 2014; Saeed et al, 2018; Schroeder & McDermott, 2014), and marine protected areas (MPAs) or fishing regulations (Bennett et al, 2020; Daw et al, 2015; Eriksson et al, 2019; Gill et al, 2019; Halpern et al, 2013). In fact, the implementation of PES initiatives that aim to establish environmental flows (e‐flows) for freshwater ecosystems have received little attention (Auerbach et al, 2014; Bellver‐Domingo et al, 2016; Hu et al, 2016; Lopes Simedo et al, 2020). E‐flows initiatives aim to keep water in rivers at specific quantities and times to help sustain the structure and function of flowing freshwater systems and are key to bending the curve on freshwater biodiversity declines (Tickner et al, 2020).…”

“…Indeed, many water‐limited and urban areas will experience increased water scarcity—where demand exceeds availability—under future climate change (Fovargue et al, 2021; He et al, 2021; Townsend & Gutzler, 2020; Zamani Sabzi, Moreno, et al, 2019). While water scarcity can potentially derail other conservation initiatives through the paradox of efficiency—where efforts to reduce water consumption through higher efficiency infrastructure fail—PES schemes could reduce water consumption through monetary conservation incentives (Grafton et al, 2018; Kahil et al, 2016; Lopes Simedo et al, 2020; Rai & Nepal, 2022). Additionally, despite the uncertainty present in future climate projections that can often complicate water resources planning and subsequently the implementation of PES initiative goals, incorporating this uncertainty into planning and focusing on low‐risk outcomes could help minimize project derailments (Fovargue et al, 2021; Herman et al, 2020; Quinn et al, 2020; Wineland et al, 2021).…”