Three essays on economic evaluation of responses to weather-induced risks in Uganda

Doctor of PhilosophyDepartment of Agricultural EconomicsAndrew P. BarkleyIn Uganda, the past five decades have been characterized by increasing temperatures, longer dry seasons, changes in the timing of rainfall with extreme events such as floods and heavy rainstorms, all of which have adverse effects on the livelihood of the rural farming community. Several strategies have been recommended for adaptation and mitigation of negative effects arising from changing weather conditions, including migration, use of weather index insurance, and changes in farm production practices, among others. However, the usability and effectiveness of the strategies are influenced by economic, social, biophysical and farmers’ behavioral factors that are examined in the three essays of this study. Given the importance of weather and labor to rural and agricultural-based economies, the first essay examines the effect of weather anomalies on the likelihood that workers migrate from rural and urban areas. By matching household survey data with weather data, and assuming exogeneity of weather variables, the effects are identified by exploiting the spatial heterogeneity of weather conditions and worker characteristics. The results remain robust to alternative model specifications, all of which show a nonlinear effect of weather anomalies on the likelihood of migration of workers from rural areas. The results show that precipitation extremes reduce the likelihood of labor migration whereas temperature extremes increase the likelihood of labor migration. This research contributes to the burgeoning literature on weather-induced migration, and the findings underscore the need to build resilience for workers. The second essay analyzes the critical temperature for coffee yield reduction and whether the effects for single-cropped coffee farms differ from those that are intercropped with bananas as shade plants. Using panel data for coffee production and weather, I exploit the spatial and temporal variations in temperature and precipitation to estimate the effects. Estimation of random-effects regression models shows a nonlinear effect of temperature and precipitation on the yield for coffee with extreme temperatures greater than 28°C resulting in yield reductions. A sensitivity analysis predicts that increases in temperature results in reductions in yield, but the reductions are less for coffee farms that are intercropped with bananas. The findings can be used to inform policy decisions and research to design interventions that reduce production risks arising from weather changes. The third essay analyzes factors that affect the adoption and renewal of weather index-based insurance contracts. It also examines farmer preferences for attributes and types of index insurance contracts. Given that the use of index insurance is relatively new in Uganda and the market is not yet well developed, the study makes use of data collected through choice laboratory experiments conducted in simulated insurance markets in Western and Central Uganda. Discrete choice models were used to analyze the data and the results showed that the ambiguity of insurance contracts reduces the likelihood of the adoption of insurance. The results also show that farmers have a higher preference for insurance offered through farmer groups, as opposed to insurance offered to individuals. The study contributes to the literature on behavioral and product-specific factors that affect the adoption of index-based insurance

Fortnightly Variability in the Transverse Dynamics of a Coastal Plain Estuary

Current velocity and water density profiles were obtained along two crossestuary transects with the purpose of determining the fortnightly variability of the transverse dynamics in a partially stratified coastal plain estuary. The profiles were measured with a towed acoustic Doppler current profiler and a conductivity-temperaturedepth recorder in the James River estuary, Virginia. The cross-estuary transects were sampled during the spring tides of October 26-27, 1996, and the ensuing neap tides of November 2-3, 1996. The transects were-4 km long, featured a bathymetry that consisted of a channel flanked by shoals, and were sampled repeatedly during two semidiurnal tidal cycles (25 hours) in order to separate semidiurnal, diurnal, and subtidal signals from the observations. This work concentrates on the subtidal transverse dynamics. The transverse baroclinic pressure gradients were larger during neap tides than during spring tides. During spring tides the advective accelerations were predominantly greater than the Coriolis accelerations, most markedly over the edges of the channel. Both effects combined with frictional influences to balance the pressure gradient in the transverse direction. During neap tides, advective accelerations were not as dominant over Coriolis accelerations as during spring tides. Also, during neap tides, Coriolis played a more relevant role, compared to spring tides, in combining with friction to balance the pressure gradient. This behavior was indicative of the momentum balance approaching gravitational circulation modified by the Earth\u27s rotation, weak friction, and nonlinear advection during neap tides. The balance became more influenced by nonlinear advection and friction and less influenced by the Earth\u27s rotation during spring tides. These results showed that transverse dynamics of a partially stratified estuary are far from being in geostrophic balanc

Separating Baroclinic Flow From Tidally Induced Flow in Estuaries

A simple method is used to separate the tidally induced and density-driven subtidal flows in a coastal plain estuary. This method is applicable to weak wind conditions and to systems with appreciable fortnightly variation of tidal amplitude. The baroclinic density-driven motion is assumed to depend on the river discharge, which generates a horizontal density gradient, and is weakened by vertical mixing, which in turn depends on tidal forcing. The barotropic tidally induced motion is assumed to be a function of the tidal amplitude. By Taylor series expansions, two equations are obtained. These equations show the dependence of the tidally induced how component on the tidal amplitude and the dependence of the density-driven flow component on the ratio between river discharge and tidal amplitude, respectively. The method is applied to water velocity data obtained in the James River, Virginia, in October-November 1996. The data cover two spring tidal cycles and two neap tidal cycles. The vertical structures, as well as the depth mean, of both tidally induced and density-driven components of the subtidal flow are obtained. Results show that the tidally induced component has a predominant seaward how in the channel and a landward flow over the shoals. The density-driven exchange how is seaward over the shoals and landward in the channel. These results are consistent with theoretical model results which show that the tidally induced component and density-driven component compete against each other. The increased tidal mixing and tidally induced exchange flow during spring tides reduce density-driven motion, which results in a weak net subtidal flow. In contrast, during neap tides, both the tidally induced flow component-of the subtidal how and tidal mixing are weak, and the tidally induced flow is overwhelmed by the density-driven flow component, which results in a stronger subtidal how. By extending the proposed method, we suggest that future studies use a least squares fitting technique to obtain an optimal estimate for the tidally induced and density-driven subtidal flow components

Convergence of Lateral Flow Along a Coastal Plain Estuary

A set of velocity profiles obtained in the James River estuary with an acoustic Doppler current profiler was used in combination with the results of an analytic tidal model to depict the appearance of surface lateral flow convergences (δv/δy) during both flood and ebb stages of the tidal cycle. The bathymetry of the estuary was characterized by a main channel and a secondary channel separated by relatively narrow shoals. Lateral surface flow convergences appeared over the edges of the channels and were produced by the phase lag of the flow in the channel relative to the shoals. Flood convergences developed in the late tidal stages and ebb convergences appeared soon after maximum currents. Most of these convergences caused fronts in the density field and flotsam lines that also appeared over the edges of the channel and that lasted \u3c2 hours. The transverse flows associated with the convergences were mostly in the same direction throughout the water column. In fact, the vertically averaged flow produced the same convergence patterns as those near the surface. The analytic tidal model reproduced well the timing and location of the convergences as observed in the James River. Model results with different bathymetry emulated the results in other estuaries, e.g., axial convergence in an estuary with a channel in the middle. This work showed that the strength of lateral convergences along the estuary was proportional to the tidal amplitude and the channel steepness. It also suggested that the convergences were produced mainly by the tidal flow interacting with the channel-shoal bathymetry, i.e., that they did not require the presence of density gradients. However, the analytic model underestimated the magnitude of the convergences and did not account for vertical circulations associated with fronts. The formation of fronts resulted from the interaction of the tidal flow with the bathymetry and the density field

Estimation of Drag Coefficient in James River Estuary Using Tidal Velocity Data from a Vessel-Towed ADCP

[1] A phase-matching method is introduced to calculate the bottom drag coefficient in tidal channels with significant lateral variation of depth. The method is based on the fact that the bottom friction in a tidal channel causes tidal velocity to have a phase difference across the channel. The calculation involves a few steps. First, the observed horizontal velocity components are analyzed to obtain the amplitude and phase of the velocity at the major tidal frequency. The phase of the longitudinal velocity is then fitted to a relationship derived from the linearized momentum balance. The drag coefficient is then calculated. This method is applicable to narrow (approximately a few kilometers wide) tidal channels without strong stratification and where the cross-channel variation of surface elevation is negligible compared to tidal amplitude. This analytic approach is easy to implement when appropriate observational data are available. It allows a spatial variation of the drag coefficient, and the resolution is only limited by that of the observations. The method is validated by identical twin experiments and applied to tidal velocity data, obtained in the James River Estuary, using an acoustic Doppler current profiler during spring tides and neap tides in October-November 1996. The obtained bottom drag coefficient ranged from 1.2 x 10(-3) to 6.9 x 10(-3) at different positions along two cross-channel transects each 4 km long and 2 to 14 m deep. The maximum drag coefficient is found in the shallowest water near the banks of the estuary, while the minimum values occur between 9 and 12 m in the center of the channel. The friction of the lateral boundary may have contributed to the apparent increase of the bottom friction on the banks. The transverse mean values of the drag coefficient ranges between 2.2 and 2.3 x 10(-3) for the spring and neap tides, respectively

Water level fluctuations and the ecosystem functioning of lakes

Hydrological regimes are key drivers of productivity and structure in freshwater ecosystems but are increasingly impacted by human activity. Using 17 published food web models of 13 African lakes as a case study, we explored relationships between seasonal and interannual water level fluctuations and 15 attributes related to ecosystem function. We interpreted our results in the context of Odum's ecosystem maturity hypothesis, as systems with higher magnitude fluctuations may be kept at an earlier maturity stage than those that are relatively stable. The data we compiled indicate that long-term changes in the hydrological regimes of African lakes have already taken place. We used Least Absolute Shrinkage and Selection Operator (LASSO) regression to examine relationships between ecosystem attributes and seven physical characteristics. Of these characteristics, interannual water level fluctuation magnitude was the most frequently retained predictor in the regression models. Our results indicate that interannual water level fluctuations are positively correlated with primary and overall production, but negatively correlated with fish diversity, transfer efficiency, and food chain length. These trends are opposite those expected with increasing ecosystem maturity. Interestingly, we found seasonal water level fluctuations to be positively correlated with biomass. An increase in standing biomass is generally associated with more mature ecosystems. However, we found that less production and biomass occurred at high trophic levels in highly fluctuating compared to relatively stable systems. This synthesis provides evidence that water level fluctuations are a key process influencing ecosystem structure and function in lakes.publishedVersio

Dis-adoption of Household Biogas technologies in Central Uganda

This work was supported by funding from the African Union Commission to the Afri-flame network under the project: Adaptation of small-scale biogas digesters for use in rural households in SubSaharan Africa, grant number AURG/2/058/2012.Peer reviewedPostprin

Future changes and uncertainty in decision-relevant measures of East African climate

The need for the development of adaptation strategies for climate change in Africa is becoming critical. For example, infrastructure with a long lifespan now needs to be designed or adapted to account for a future climate that will be different from the past or present. There is a growing necessity for the climate information used in decision making to change from traditional science-driven metrics to decision-driven metrics. This is particularly relevant in East Africa, where limited adaptation and socio-economic capacity make this region acutely vulnerable to climate change. Here, we employ an interdisciplinary consultation process to define and analyse a number of such decision-oriented metrics. These metrics take a holistic approach, addressing the key East African sectors of agriculture, water supply, fisheries, flood management, urban infrastructure and urban health. A multifaceted analysis of multimodel climate projections then provides a repository of user-focused information on climate change and its uncertainties, for all metrics and seasons and two future time horizons. The spatial character and large intermodel uncertainty of changes in temperature and rainfall metrics are described, as well as those of other relevant metrics such as evaporation and solar radiation. Intermodel relationships amongst metrics are also explored, with two clear clusters forming around rainfall and temperature metrics. This latter analysis determines the extent to which model weights could, or could not, be applied across multiple climate metrics. Further work must now focus on maximising the utility of model projections, and developing tailored risk-based communication strategies

Scientific understanding of East African climate change from the HyCRISTAL project

Integrating Hydro-Climate Science into Policy Decisions for Climate-Resilient Infrastructure and Livelihoods in East Africa (HyCRISTAL) is a Future Climate for Africa (FCFA) project funded to deliver new understanding of East African climate change and its impacts, and to demonstrate use of climate change information in long-term decision-making in the region. Here, we briefly summarise key findings from HyCRISTAL so far on climate change, as well as key findings from the pan-African FCFA project “IMPALA” relevant to East Africa, both in the context of previous literature on the topic

Scientific understanding of East African climate change from the HyCRISTAL project

Integrating Hydro-Climate Science into Policy Decisions for Climate-Resilient Infrastructure and Livelihoods in East Africa (HyCRISTAL) is a Future Climate for Africa (FCFA) project funded to deliver new understanding of East African climate change and its impacts, and to demonstrate use of climate change information in long-term decision-making in the region. Here, we briefly summarise key findings from HyCRISTAL so far on climate change, as well as key findings from the pan-African FCFA project “IMPALA” relevant to East Africa, both in the context of previous literature on the topic