Koffi Djaman | Africa Rice Center (original) (raw)
Papers by Koffi Djaman
Transactions of the ASABE, 2015
Applied Engineering in Agriculture, 2022
<p>Global warming impacts are known as increasing in rainfall magnitude and frequen... more <p>Global warming impacts are known as increasing in rainfall magnitude and frequency that lead to more intense and frequent river flooding. In recent years, there is an upward trend of floods in West African regions. As result, many countries like Togo and Benin have had catastrophic floods that affected thousands of people with loss of lives, damages, and properties. Mono catchment is indeed subject to flooding due to anthropogenic and natural climate changes impacts. This study aims to predict stream&#64258;ow for the period between 1990 and 2020 using hydrological modeling at gauge stations; to analyze flood frequency and magnitudes over the Mono catchment for the historical period through an investigation of hydroclimate indices. Moreover, projected changes in floods hydroclimate indices in the catchment under representative concentration pathway (RCP) from a multi-model ensemble model are investigated. The results show that hydrological modeling reproduces seasonal streamflow with acceptable performance with Kling-Gupta Efficiency (KGE) and percent over calibration and validation periods. Finally, an upward flood frequency and magnitude are observed both for historical and future periods. The outcomes of this study suggest an urgent need to improve the functionality of early warning systems and increase societal resilience to warming climates over the catchment through sustainable policy strategies and governance measures.</p><p><strong>Keywords</strong>: Flood Frequency and magnitude, Flood forecasting, Mono catchment, Togo-Benin</p>
2022 Houston, Texas July 17-20, 2022
Journal of Water and Climate Change, Apr 9, 2015
2022 Houston, Texas July 17-20, 2022, 2022
Transactions of the ASABE, Oct 27, 2016
Italian Journal of Agronomy, Jan 3, 2019
Irrigation and Drainage Systems Engineering, 2018
Journal of Irrigation and Drainage Engineering-asce, Feb 1, 2023
Journal of Irrigation and Drainage Engineering-asce, Feb 1, 2023
Agronomy
Actual crop evapotranspiration (ETa) is measured or estimated using different methods, and its ac... more Actual crop evapotranspiration (ETa) is measured or estimated using different methods, and its accuracy is critical for water management under precision agriculture. The objective of this study was to compare maize ETa estimated by the two-step approach using a locally developed crop coefficient curve with satellite-retrieved evapotranspiration by six models incorporated in the OpenET to identify the best evapotranspiration estimation alternatives to the two-step approach for water management in northern New Mexico. Maize (Zea mays L.) was planted at the NMSU Agricultural Science Center at Farmington from 2017 to 2022 and uniformly managed across years. Water management in plants was based on maize’s actual evapotranspiration estimated as the product of the reference evapotranspiration and the local crop coefficient, which is described as a third-order polynomial function of the accumulated heat units by maize plants. For the same growing seasons, maize ETa was retrieved from satell...
Bulletin - Agricultural Experiment Station, New Mexico, 2018
International Soil and Water Conservation Research
Journal of New Seeds, 2010
Agronomy
Crop evapotranspiration (ETa) is the main source of water loss in farms and watersheds, and with ... more Crop evapotranspiration (ETa) is the main source of water loss in farms and watersheds, and with its effects felt at a regional scale, it calls for irrigation professionals and water resource managers to accurately assess water requirements to meet crop water use. On a multi-crop commercial farm, different factors affect cropland allocation, among which crop evapotranspiration is one of the most important factors regarding the seasonally or annually available water resources for irrigation in combination with the in-season effective precipitation. The objective of the present study was to estimate crop evapotranspiration for four major crops grown on the Navajo Agricultural Products Industry (NAPI) farm for the 2016–2010 period to help crop management in crop plant allocation based on the different objectives of the NAPI. The monthly and seasonal satellite-based ETa of maize, potatoes, dry beans, and alfalfa were retrieved and compared using the analysis of variance and the least si...
Irrigation & Drainage Systems Engineering, 2018
The effects of full and limited irrigation practices on maize growth parameters, yield, actual cr... more The effects of full and limited irrigation practices on maize growth parameters, yield, actual crop evapotranspiration (ETa), crop coefficients, and nutrient uptake dynamics were investigated. Field experiments were conducted under a 4-span hydraulic and continuous move center pivot irrigation system at the University of Nebraska-Lincoln, South Central Agricultural Laboratory (SCAL) during the growing seasons in 2009 and 2010. Four irrigation regimes 100% of the fully-irrigated treatment (FIT), 75% FIT, 60% FIT, 50% FIT and rainfed treatment were evaluated. Maize yields varied from 9.05 tons/ha for the rainfed treatment to 15.51 tons/ha for the 100% FIT in 2009 and 11.74 to 15.45 tons/ha for the same treatments in 2010. There was no statistically significant difference between the 75% FIT and the 100% FIT in terms of grain yield. Crop evapotranspiration increased with irrigation amounts and ranged from 509 to 645 mm in 2009 and from 690 to 748 mm in 2010. In terms of performance in crop water productivity, the 60% and 75% FIT treatments were comparable to the full irrigated treatment and are viable approaches in increasing crop water productivity of maize under these experimental, soil and crop management, and climatic conditions. On average, 60%FIT resulted in the highest irrigation water use efficiency of 4.53 kg/m3. Mid-season crop grass- and alfalfa-reference crop coefficients (Kco and Kcr) showed variability with the irrigation treatment. The mid-season Kco ranged from 1.08 to 1.26 and the mid-season Kcr ranged between 0.92 and 1.05. Nitrogen uptake ranged from 154 to 253 Kg/ha and 182 to 270 Kg/ha in 2009 and 2010 respectively. The FIT resulted in the highest and the rainfed treatment had the lowest nitrogen uptake in both years. The FIT had the highest phosphorus uptake with 39 Kg/ha and 53 Kg/ha in 2009 and 2010, respectively. Better potassium uptake was observed in 2010 and it ranged from 414 to 637 Kg/ha while it ranged from 333 to 367 Kg/ha in 2009
Transactions of the ASABE, 2015
Applied Engineering in Agriculture, 2022
<p>Global warming impacts are known as increasing in rainfall magnitude and frequen... more <p>Global warming impacts are known as increasing in rainfall magnitude and frequency that lead to more intense and frequent river flooding. In recent years, there is an upward trend of floods in West African regions. As result, many countries like Togo and Benin have had catastrophic floods that affected thousands of people with loss of lives, damages, and properties. Mono catchment is indeed subject to flooding due to anthropogenic and natural climate changes impacts. This study aims to predict stream&#64258;ow for the period between 1990 and 2020 using hydrological modeling at gauge stations; to analyze flood frequency and magnitudes over the Mono catchment for the historical period through an investigation of hydroclimate indices. Moreover, projected changes in floods hydroclimate indices in the catchment under representative concentration pathway (RCP) from a multi-model ensemble model are investigated. The results show that hydrological modeling reproduces seasonal streamflow with acceptable performance with Kling-Gupta Efficiency (KGE) and percent over calibration and validation periods. Finally, an upward flood frequency and magnitude are observed both for historical and future periods. The outcomes of this study suggest an urgent need to improve the functionality of early warning systems and increase societal resilience to warming climates over the catchment through sustainable policy strategies and governance measures.</p><p><strong>Keywords</strong>: Flood Frequency and magnitude, Flood forecasting, Mono catchment, Togo-Benin</p>
2022 Houston, Texas July 17-20, 2022
Journal of Water and Climate Change, Apr 9, 2015
2022 Houston, Texas July 17-20, 2022, 2022
Transactions of the ASABE, Oct 27, 2016
Italian Journal of Agronomy, Jan 3, 2019
Irrigation and Drainage Systems Engineering, 2018
Journal of Irrigation and Drainage Engineering-asce, Feb 1, 2023
Journal of Irrigation and Drainage Engineering-asce, Feb 1, 2023
Agronomy
Actual crop evapotranspiration (ETa) is measured or estimated using different methods, and its ac... more Actual crop evapotranspiration (ETa) is measured or estimated using different methods, and its accuracy is critical for water management under precision agriculture. The objective of this study was to compare maize ETa estimated by the two-step approach using a locally developed crop coefficient curve with satellite-retrieved evapotranspiration by six models incorporated in the OpenET to identify the best evapotranspiration estimation alternatives to the two-step approach for water management in northern New Mexico. Maize (Zea mays L.) was planted at the NMSU Agricultural Science Center at Farmington from 2017 to 2022 and uniformly managed across years. Water management in plants was based on maize’s actual evapotranspiration estimated as the product of the reference evapotranspiration and the local crop coefficient, which is described as a third-order polynomial function of the accumulated heat units by maize plants. For the same growing seasons, maize ETa was retrieved from satell...
Bulletin - Agricultural Experiment Station, New Mexico, 2018
International Soil and Water Conservation Research
Journal of New Seeds, 2010
Agronomy
Crop evapotranspiration (ETa) is the main source of water loss in farms and watersheds, and with ... more Crop evapotranspiration (ETa) is the main source of water loss in farms and watersheds, and with its effects felt at a regional scale, it calls for irrigation professionals and water resource managers to accurately assess water requirements to meet crop water use. On a multi-crop commercial farm, different factors affect cropland allocation, among which crop evapotranspiration is one of the most important factors regarding the seasonally or annually available water resources for irrigation in combination with the in-season effective precipitation. The objective of the present study was to estimate crop evapotranspiration for four major crops grown on the Navajo Agricultural Products Industry (NAPI) farm for the 2016–2010 period to help crop management in crop plant allocation based on the different objectives of the NAPI. The monthly and seasonal satellite-based ETa of maize, potatoes, dry beans, and alfalfa were retrieved and compared using the analysis of variance and the least si...
Irrigation & Drainage Systems Engineering, 2018
The effects of full and limited irrigation practices on maize growth parameters, yield, actual cr... more The effects of full and limited irrigation practices on maize growth parameters, yield, actual crop evapotranspiration (ETa), crop coefficients, and nutrient uptake dynamics were investigated. Field experiments were conducted under a 4-span hydraulic and continuous move center pivot irrigation system at the University of Nebraska-Lincoln, South Central Agricultural Laboratory (SCAL) during the growing seasons in 2009 and 2010. Four irrigation regimes 100% of the fully-irrigated treatment (FIT), 75% FIT, 60% FIT, 50% FIT and rainfed treatment were evaluated. Maize yields varied from 9.05 tons/ha for the rainfed treatment to 15.51 tons/ha for the 100% FIT in 2009 and 11.74 to 15.45 tons/ha for the same treatments in 2010. There was no statistically significant difference between the 75% FIT and the 100% FIT in terms of grain yield. Crop evapotranspiration increased with irrigation amounts and ranged from 509 to 645 mm in 2009 and from 690 to 748 mm in 2010. In terms of performance in crop water productivity, the 60% and 75% FIT treatments were comparable to the full irrigated treatment and are viable approaches in increasing crop water productivity of maize under these experimental, soil and crop management, and climatic conditions. On average, 60%FIT resulted in the highest irrigation water use efficiency of 4.53 kg/m3. Mid-season crop grass- and alfalfa-reference crop coefficients (Kco and Kcr) showed variability with the irrigation treatment. The mid-season Kco ranged from 1.08 to 1.26 and the mid-season Kcr ranged between 0.92 and 1.05. Nitrogen uptake ranged from 154 to 253 Kg/ha and 182 to 270 Kg/ha in 2009 and 2010 respectively. The FIT resulted in the highest and the rainfed treatment had the lowest nitrogen uptake in both years. The FIT had the highest phosphorus uptake with 39 Kg/ha and 53 Kg/ha in 2009 and 2010, respectively. Better potassium uptake was observed in 2010 and it ranged from 414 to 637 Kg/ha while it ranged from 333 to 367 Kg/ha in 2009