Land Use Effect on the CN Model Parameters in a Tropical Dry Environment

• Published in: Water resources management Vol. 31; no. 13; pp. 4103 - 4116
• Main Authors: Andrade, E. M, Araújo Neto, J. R, Guerreiro, M. J. S, Santos, J. C. N, Palácio, H. A. Q
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 01-10-2017; Springer Nature B.V
• Subjects: Atmospheric Sciences; Catchment area; Catchments; Civil Engineering; Computer simulation; Data processing; Dry forests; Earth and Environmental Science; Earth Sciences; Environment; Forest management; Forests; Geotechnical Engineering & Applied Earth Sciences; Hydrogeology; Hydrologic data; Hydrologic models; Hydrology; Hydrology/Water Resources; Impact analysis; Land use; Mathematical models; Monte Carlo simulation; Natural resources; Parameter sensitivity; Parameters; Rain; Rainfall; Rainfall-runoff relationships; Rainforests; Reliability analysis; Resource conservation; Runoff; Semiarid environments; Semiarid lands; Simulation; Soil; Statistical methods; Tropical climate; Tropical forests; Groundcover; Hydrologic processes; Curve number; Initial abstraction ratio; Runoff coefficient
• ISSN: 0920-4741; 1573-1650
• DOI: 10.1007/s11269-017-1732-4

Dry tropical forests account for over 1,000,000 km
2
, and there is still lack of knowledge on their hydrologic processes. The curve number
(
CN) hydrologic model developed by the Natural Resources Conservation Service (NRCS) is widely applied for runoff determination in various parts of the world, but not so in tropical semiarid regions. This study analyzes the impact of land use changes on the CN model in a tropical semiarid environment, in two catchments of native dry tropical forest and thinned dry tropical forest land use from 2009 to 2012. The CN model was calibrated and validated for the NRCS recommended initial abstraction ratio λ = 0.2, and for λ evaluated from rainfall and runoff data. A reliability analysis was performed using Monte Carlo simulation. Model goodness-of-fit was assessed with statistical criteria. A total of 42 and 40 rainfall-runoff events were analyzed for the native and thinned dry tropical forest, respectively. Characteristic λ values of 0.15 and 0.11 were determined for the two respective catchments. Although CN values were similar for both land uses, CN
λ=0.20
 = 80 and CN
median λ
 = 77, the thinned catchment showed a higher CN model parameters variability. The CN model was more sensitive to variations of CN values than to those of λ. This study showed that no matter the vegetation management in a dry tropical forest environment, modeled runoff is not affected by λ, but rather affected by CN, which represents soil, landuse and management.