Estimating river flows at ungauged sites is generally recognised as an important area of research. In countries or regions with rapid land development and sparse hydrological gauging networks, three particular challenges may arise-data scarcity, data quality, and hydrological non-stationarity. Using data from 44 gauged sub-catchments of the upper Ping catchment in northern Thailand from the period 1995-2006, three relevant flow response indices (runoff coefficient, base flow index and seasonal elasticity of flow) were regionalised by regression against available catchment properties. The runoff coefficient was the most successfully regionalised, followed by base flow index and lastly the seasonal elasticity. The non-stationarity (represented by the differences between two 6-year sub-periods) was significant both in the flow response indices and in land use indices; however relationships between the two sets of indices were weak. The regression equations derived from regionalisation were not helpful in predicting the non-stationarity in the flow indices except somewhat for the runoff coefficient. A partly subjective data quality scoring system was devised, and showed the clear influence of rainfall and flow data quality on regionalisation uncertainty. Recommendations towards improving data support for hydrological regionalisation in Thailand include more relevant soils databases, improved records of abstractions and investment in the gauge network. Widening of the regionalisation beyond the upper Ping and renewed efforts at using remotely sensed rainfall data are other possible ways forward.

Agriculture is sensitive to drought and associated social, environmental and economic impacts. Finance-based interventions aim to support farmers affected by drought; however, the extent to which such tools encourage resilience to this natural hazard is unclear. This paper systematically reviews evidence on links between financial interventions to mitigate drought-related impacts and adaptation towards longer-term resilience. We focus on tropical Asia where agriculture contributes significantly to national economies and is a primary source of livelihood in a region subject to high climate variability and episodic drought. Guided by Population, Intervention, Comparator and Outcome criteria, we identify and review 43 regionally specific articles that describe a range of financial interventions. Through thematic synthesis, we document the interventions’ associations with micro-level and macro-level outcomes. The results reveal how some interventions helped sustain household incomes and crop yield (e.g. through farm investments that increased productivity) through drought, whilst others encouraged adaptive behaviours. At a macro-level, there were challenges associated with government budgets and scheme administration, with the longevity of many schemes difficult to sustain. From fragmented evidence, this review reasons that there can be challenging policy trade-offs for institutions between supporting livelihoods and economic growth whilst also protecting the environment—highlighting the interdependence of systems’ resilience and variability in actors’ capacity to adapt. Low-regret interventions that integrate existing community adaptive practices, engage with farmers’ needs and prioritise extension support may encourage more desirable counteractions to drought; however, further research is needed to establish the role of such interventions.

The intensification of drought affects agricultural production, leading to economic losses, environmental degradation and social impacts. To move toward more resilient system configurations requires understanding the processes that shape farmers' adaptation amidst complex institutional contexts. Social networks are an important part of collective action for supporting adaptive capacity and there are continuing calls to strengthen network connectivity for agricultural governance under the impacts of climate change. Through a survey of 176 farmers in northern Thailand, we explore the extent to which the characteristics of information shared in a catchment advice network are associated with adaptations. Statistical analyses reveal the perceived efficacy of communications as well as farmers’ relative closeness in the advice network to be positively associated with adaptation to drought. We identify a capacity for local actors to bridge information bottlenecks in the network and opportunities for institutions to enhance their dissemination of information to reach less networked farmers. We find that not all adaptations are perceived as effective against future drought and infer opportunities to support engagement with extension services, encourage the sharing of local knowledge and experience and devise policy and interventions to strengthen advice networks for more resilient agricultural systems. This article is part of the Royal Society Science+ meeting issue ‘Drought risk in the Anthropocene’.

This study presented a two-year data set of sensible heat and water vapor fluxes above a humid subtropical montane Cypress forest, located at 1650 m a.s.l. in northeastern Taiwan. The focuses of this study were to investigate (1) the diurnal and seasonal variations of canopy resistance and fluxes of sensible heat and water vapor above this forest; and (2) the mechanism of why a fixed canopy resistance could work when implementing the Penman–Monteith equation for diurnal hourly evapotranspiration estimation. Our results showed distinct seasonal variations in canopy resistance and water vapor flux, but on the contrary, the sensible heat flux did not change as much as the water vapor flux did with seasons. The seasonal variation patterns of the canopy resistance and water vapor flux were highly coupled with the meteorological factors. Also, the results demonstrated that a constant (fixed) canopy resistance was good enough for estimating the diurnal variation of evapotranspiration using Penman–Monteith equation. We observed a canopy resistance around 190 (s/m) for both the two warm seasons; and canopy resistances were around 670 and 320 (s/m) for the two cool seasons, respectively. In addition, our analytical analyses demonstrated that when the average canopy resistance is higher than 200 (s/m), the Penman–Monteith equation is less sensitive to the change of canopy resistance; hence, a fixed canopy resistance is suitable for the diurnal hourly evapotranspiration estimation. However, this is not the case when the average canopy resistance is less than 100 (s/m), and variable canopy resistances are needed. These two constraints (200 and 100) were obtained based on purely analytical analyses under a moderate meteorological condition (Rn = 600 W·m−2, RH = 60%, Ta = 20°C, U = 2 m·s−1) and a measurement height around two times of the canopy height.

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