Water and Emotion: Testing a New Approach for Monitoring Water Security Among Afar Pastoralists in Ethiopia

Ethiopia has over 12 million pastoralists that raise livestock and move their herds in search of fresh pasture and water. This way of life is especially vulnerable to climate change as drought and shifts in seasonal rainfall patterns are changing the distribution and availability of these resources in pastoralist regions. The dynamic use of water within these settings is also not well-understood or captured by conventional water sector monitoring systems, which prevents appropriate supportive interventions and policies to be delivered. This paper presents results from a study into a new approach to measuring water security that focuses on assessing the emotional response of pastoralist populations to their water security situation. Formative research involving focus groups and interviews was followed by a survey of 148 pastoralists to assess their emotional response to different water security dimensions. The results indicate that emotional response can be used to elicit valuable insights into water security and provide a powerful complement to conventional water security monitoring techniques. Using the approach, we show a strong relationship between variation in seasonal water access and reported emotional response. Negative emotions also strongly associate with the most laborious methods of collecting water such as scoop holes and hand dug wells, whereas positive emotions were associated with access to higher quantities of water. Access to equines for carrying water was associated with more positive emotional well-being indicating a route to water security improvement in this context could be through the provision of donkeys and mules for water carrying. The paper discusses the value of using an emotion-based approach to capture experiences of water security alongside more conventional objective measures, especially among populations with water use patterns that continue to be poorly understood.

Machine Learning Modeling of Water Use Patterns in Small Disadvantaged Communities

Water use patterns were explored for three small communities that are located in proximity to agricultural fields and rely on their local wells for potable water supply. High-resolution water use data, collected over a four-year period, revealed significant temporal variability. Monthly, daily, and hourly water use patterns were well described by autoregressive moving average (ARMA) models. Model development was supported by unsupervised clustering analysis via self-organizing maps (SOMs) that revealed similarities of water use patterns and confirmed the time-series water use model attributes. The inclusion of ambient temperature and rainfall as model attributes improved ARMA model performance for daily and hourly water use from R2 ~0.86–0.87 to 0.94–0.97 and from R2 ~0.85–0.89 to 0.92–0.98, respectively. Water use predictions for an entire year forward in time was feasible demonstrating ARMA models’ performance of (i) R2 ~0.90–0.94 and average absolute relative error (AARE) of ~2.9–4.9% for daily water use, and (ii) R2 ~0.81–0.95 and AARE ~1.9–3.8% for hourly water use. The study suggests that ARMA modeling should be useful for analysis of temporally variable water use in support of water source management, as well as assessing capacity building for small water systems including water treatment needs and wastewater handling.

Interspecific soil water partitioning as a driver of increased productivity in a diverse mixed Mediterranean forest

<p>It has been assumed that mixing of species with high physiological diversity reduces competition over water and light resources, compared to single-species forests. Although several mechanisms to explain this observation have been proposed, empiric evidence is lacking. Here we studied water-use dynamics at a monthly resolution for two years in five key tree species in a mature, mixed, evergreen, Mediterranean forest. Root distribution was measured with DNA barcoding and soil cores. Measurements at the tree-scale were up-scaled using an ecosystem model of coupled water, carbon and energy fluxes (Regional Hydro Ecologic Simulation System, RHESSys). Tree species showed contrasting water-use patterns, with year-round activity in angiosperms, and mostly wet season-activity in gymnosperms. Water-use patterns matched the rooting patterns, with the deep- and shallow-rooted Ceratonia and Cupressus, showing year-round and seasonal behaviors, respectively. RHESSys simulations captured well the species-specific behaviors in the mixed forest, and were further applied to simulate monocultures of each of the species, which proved less productive than the mixed forest. Our results provide evidence for niche partitioning of the soil water resource among co-habiting tree species. This partitioning is driven by spatiotemporal species differences in rooting depth and eco-physiology, and facilitates the higher productivity of the mixed forest.</p>

Exploring the Influence of Biological Traits and Environmental Drivers on Water Use Variations across Contrasting Forests

Understanding species-specific water use patterns across contrasting sites and how sensitivity of responses to environmental variables changes for different species is critical for evaluating potential forest dynamics and land use changes under global change. To quantify water use patterns and the sensitivity of tree transpiration to environmental drivers among sites and species, sap flow and meteorological data sets from three contrasting climatic zones were combined and compared in this analysis. Agathis australis from NZHP site, Schima wallichii Choisy (native) and Acacia mangium Willd (exotic) from CHS site, Liquidamber formosana Hance, Quercus variabilis Blume and Quercus acutissima Carruth from CJGS site were the dominant trees chosen as our study species. Biological traits were collected to explain the underlying physiological mechanisms for water use variation. Results showed that the strongest environmental drivers of sap flow were photosynthetically active radiation (PAR), vapor pressure deficit (VPD) and temperature across sites, indicating that the response of water use to abiotic drivers converged across sites. Water use magnitude was site specific, which was controlled by site characteristics, species composition and local weather conditions. The species with higher sap flow density (Fd) generally had greater stomatal conductance. Native deciduous broadleaved species had a higher Fd and faster response to stomatal regulation than that of native evergreen broadleaved species (S. wallichii) and conifer species A. australis. The analysis also showed that exotic species (A. mangium) consumed more water than native species (S. wallichii). Trees with diffuse porous and lower wood density had relatively higher Fd for angiosperms, suggesting that water use was regulated by physiological differences. Water use characteristics across sites are controlled by both external factors such as site-specific characteristics (local environmental conditions and species composition) and internal factors such as biological traits (xylem anatomy, root biomass and leaf area), which highlights the complexity of quantifying land water budgets for areas covered by different species.