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. 2016 Mar 22;11(3):e0150626.
doi: 10.1371/journal.pone.0150626. eCollection 2016.

A Regional Model for Malaria Vector Developmental Habitats Evaluated Using Explicit, Pond-Resolving Surface Hydrology Simulations

Ernest Ohene Asare  1   2 , Adrian Mark Tompkins  2 , Arne Bomblies  3
Affiliations

A Regional Model for Malaria Vector Developmental Habitats Evaluated Using Explicit, Pond-Resolving Surface Hydrology Simulations

Ernest Ohene Asare et al. PLoS One. .

Abstract

Dynamical malaria models can relate precipitation to the availability of vector breeding sites using simple models of surface hydrology. Here, a revised scheme is developed for the VECTRI malaria model, which is evaluated alongside the default scheme using a two year simulation by HYDREMATS, a 10 metre resolution, village-scale model that explicitly simulates individual ponds. Despite the simplicity of the two VECTRI surface hydrology parametrization schemes, they can reproduce the sub-seasonal evolution of fractional water coverage. Calibration of the model parameters is required to simulate the mean pond fraction correctly. The default VECTRI model tended to overestimate water fraction in periods subject to light rainfall events and underestimate it during periods of intense rainfall. This systematic error was improved in the revised scheme by including the a parametrization for surface run-off, such that light rainfall below the initial abstraction threshold does not contribute to ponds. After calibration of the pond model, the VECTRI model was able to simulate vector densities that compared well to the detailed agent based model contained in HYDREMATS without further parameter adjustment. Substituting local rain-gauge data with satellite-retrieved precipitation gave a reasonable approximation, raising the prospects for regional malaria simulations even in data sparse regions. However, further improvements could be made if a method can be derived to calibrate the key hydrology parameters of the pond model in each grid cell location, possibly also incorporating slope and soil texture.

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Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Fig 1
Fig 1. Schematic of the modified hydrology scheme adapted from Asare et al. [48].
Precipitation (P) is assumed to fall homogeneously across the grid-cell. In some locations the rainfall drains into stream/river catchments, while the remainder either contributes directly to pools or falls within local catchments for ponds, in which case only a proportion may reach the ponds via surface runoff. The sink of pond coverage is via the loss of water due to overflow (O), infiltration (I) and evaporation (E).
Fig 2
Fig 2. An example of daily HYDREMATS simulated water depth evolution of individual ponds over the study domain for four consecutive days in each year.
The Julian day and rainfall recorded for the selected days in 2005 (left panel) and 2006 (right panel) are provided under each plot.
Fig 3
Fig 3. RMSE between HYDREMATS and VECTRI schemes (with varying tunable parameters) simulated daily water fraction.
Left panel: VECTRI hydrology V1.2.6, middle panel: V1.3.0 varying maximum infiltration Imax with a constant CN of 85 and right panel: V1.3.0 varying CN with constant Imax of 500 mm day−1.
Fig 4
Fig 4. Comparison of 7-day moving average time series of simulated water fraction from HYDREMATS and VECTRI schemes.
The VECTRI schemes time series were generated from a sets of VECTRI calibrated parameters that minimize RMSE values with respect to HYDREMATS. (a) V1.2.6, (b) V1.3.0 varying maximum infiltration (Imax) assuming a constant CN of 85, (c) V1.3.0 varying CN at a constant Imax of 500 mm day−1, and (d) the difference between HYDREMATS and VECTRI.
Fig 5
Fig 5. Comparison of 7-day moving average time series of simulated mosquito vector abundance from HYDREMATS and VECTRI schemes.
For the VECTRI experiments, identical calibrated parameters as for Fig 4 were used.
Fig 6
Fig 6. Comparison of 7-day moving average time series between VECTRI simulated water fraction driven by station rainfall, TRMM 3B42 and FEWS RFE2 rainfall estimates.
(a) TRMM and FEWS RFE2, (b) V.1.2.6 scheme predicted water fraction and (d) V.1.3.0 scheme predicted water fraction.
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References

    1. Fillinger U, Sonye G, Killeen GF, Knols BGJ, Becker N. The practical importance of permanent and semipermanent habitats for controlling aquatic stages of Anopheles gambiae sensu lato mosquitoes: operational observations from a rural town in western Kenya. Tropical Medicine & International Health. 2004;9(12):1274–1289. 10.1111/j.1365-3156.2004.01335.x - DOI - PubMed
    1. Minakawa N, Sonye G, Yan G. Relationships between occurrence of Anopheles gambiae sl (Diptera: Culicidae) and size and stability of larval habitats. Journal of medical entomology. 2005;42(3):295–300. - PubMed
    1. Sattler MA, Mtasiwa D, Kiama M, Premji Z, Tanner M, Killeen GF, et al. Habitat characterization and spatial distribution of Anopheles sp. mosquito larvae in Dar es Salaam (Tanzania) during an extended dry period. Malaria Journal. 2005;4(1):4 10.1186/1475-2875-4-4 - DOI - PMC - PubMed
    1. Mutuku FM, Bayoh MN, Gimnig JE, Vulule JM, Kamau L, Walker ED, et al. Pupal habitat productivity of Anopheles gambiae complex mosquitoes in a rural village in western Kenya. The American journal of tropical medicine and hygiene. 2006;74(1):54–61. - PubMed
    1. Awolola T, Oduola A, Obansa J, Chukwurar N, Unyimadu J. Anopheles gambiae ss breeding in polluted water bodies in urban Lagos, southwestern Nigeria. Journal of Vector Borne Diseases. 2007;44(4):241 - PubMed

Publication types

Grants and funding

EOA was funded by two International Centre of Theoretical Physics (ICTP) programme, namely the Italian government’s funds-in-trust programme and the ICTP PhD Sandwich Training and Educational Programme (STEP). The study was also partly funded by two European Union Seventh Framework Programmes projects: HEALTHY FUTURES under the grant agreement number 266327 and QWeCI (Quantifying Weather and Climate Impacts on health in developing countries) under the grant agreement number 243964.