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In recent decades, the impact of land use on water-related ecosystem services has become a prominent issue in the watershed management in the context of climate change. Based on literature review, Chang et al. (2016) concluded that changes in the distribution and value of water over space and time, which are associated with changing climatic conditions, will likely have substantial effects on water-related ecosystem services. However, the impacts of climate change will differ depending on the adaptive capacities of the specific biophysical and social system. 

In incentives or payments for environmental services schemes for watershed management, downstream water users pay or encourage upstream famers to protect and/or restore hydrological services through improved land management practices. Payments for watershed services (PWS) should be conditional on a measurable increase in the watershed services (Engel et al., 2008; Wunder, 2015). However, in the absence of hydrological monitoring, it is difficult for PWS schemes to detect changes in hydrology with any confidence and attribute any changes to the sustainable land management practices implemented (Asquith et al., 2008). As a result, the monitoring of most PWS schemes is based on compliance, rather than evidence that sustainable land management practices have had a positive impact (Smith et al., 2013; Ponette-Gonzalez et al., 2014; Porras et al., 2013). As upstream land users implement the sustainable land management required by the PWS agreement they are paid, even if there is no indication that the expected improvements in watershed services have materialized. This places the risks of a PWS scheme primarily on the buyers for watershed services. It is important for a PWS scheme to be robust and fair and achieve the principle of conditionality of payement schemes based on hydrological monitoring results. In the East African region, many proposed PWS schemes have not made it past the design phase and, for those that have, hydrological monitoring of the impacts has been generally limited. 

It has proven difficult to successfully develop a payment for environmental services scheme in which payments are conditional on measured improvements in watershed services. A successful PWS scheme depends upon a shared perception, by both upstream farmers and downstream water users, of the watershed services provided by a catchment and of the actions necessary to restore and protect these services (Jeanes et al., 2006). If developed successfully, payment for environmental services schemes can provide a framework both for the funding and implementation of sustainable land management and for monitoring its hydrological impacts. The establishment of a baseline that encapsulates the hydrological variability of a catchment is the foundation upon which a PWS scheme should ideally be developed (Smith et al., 2013). A robust baseline allows the additional benefits delivered by a PWS scheme to be estimated by calculating the net positive impact of interventions relative to the situation where they were not implemented (Porras et al., 2013). A more accurate estimation of the benefits and potential negative externalities also makes it easier to assess the financial feasibility of a scheme, and in particular whether the benefits gained by downstream users are worth the payments they made. However, many PWS schemes do not undertake hydrological monitoring due to the cost and the limited amount of time available to establish a baseline prior to any interventions (Ponette-Gonzalez et al., 2014). 

The Kagera Transboundary Agro-ecosystem Management Project (Kagera TAMP) (see Case Study 2) undertook a study whose primary aim was to quantify and evaluate the hydrological impacts of sustainable land management on a small catchment in Rwanda. This was achieved primarily through the establishment of a participatory monitoring network, the acquisition of secondary information from open-access databases, the application of a hydrological model, and scenario building. In addition, the role that local participation could play in the monitoring was investigated alongside the possibility of scaling up sustainable land management and hydrological monitoring to the wider meso-scale catchment, potentially through the development of a PWS scheme.

The findings and main suggestions from the Kagera TAMP to scale up of sustainable land management to an integrated landscape management approach are presented below. 

• The discharge of the catchment responds rapidly to rainfall and appears to be related closely to surface water and groundwater interactions and connectivity. Turbidity response and other observations support the conclusion that, in recent years, land-use change, land degradation and erosion have significantly altered the hydrology of the catchment. In particular, increased hydrological connectivity, caused in part by the expanded gully and footpath networks, allows runoff and sediment to be conveyed more quickly to the stream network instead of infiltrating in the ground and contributing to surface water and ground water supply. 
• The monitoring provided some evidence that ex situ rain water harvesting structures can combat existing soil erosion by water processes by reducing runoff for smaller rainfall events. Modelling and scenario analysis suggest that the combination of in situ and ex situ technologies can significantly reduce erosion and runoff even for relatively large rainfall events. 
• For any sustainable land management work to be successful, local acceptance of the sustainable land management interventions and trust between key stakeholders is essential (Nyssen et al., 2007; Fisher et al., 2010; Bond and Meyers, 2010). Acceptance can be encouraged by involving the local community in monitoring, and increasing their knowledge of the hydrological benefits of sustainable land management. 
• Overall, a combination of participatory monitoring, the use of new sources of data and modelling, and the installation of some automated equipment looks to be the best way to inform and track the implementation of sustainable land management across the entire Yanze catchment in Rwanda and in other areas of the Kagera Basin. In turn, the data and analysis will provide a substantive basis by which inform future incentives or payments for ecosystem services arrangements between water users downstream and land users upstream.