Table 3.
Impact of irrigation infrastructure on agricultural productivity and cropland expansion
| Agricultural Productivity | Cropland Area | |||
| X = 2 | X = 3 | X = 4 | ||
| No. upstream dams | 0.0743* | 0.037420* | 0.038960*** | 0.028461*** |
| (0.031) | (0.015) | (0.007) | (0.005) | |
| Wet anomaly | 0.1886*** | |||
| (0.022) | ||||
| Wet anomaly × no. upstream dams | −1.0743*** | |||
| (0.220) | ||||
| X + wet anomalies | 0.000123 | 0.000528 | 0.001135* | |
| (0.000) | (0.000) | (0.000) | ||
| X + wet anomalies × no. upstream dams | 0.001480 | −0.010607 | −0.013812 | |
| (0.013) | (0.013) | (0.021) | ||
| Dry anomaly | −0.1338*** | |||
| (0.009) | ||||
| Dry anomaly × no. upstream dams | 0.1905** | |||
| (0.070) | ||||
| X + dry anomalies | 0.001124** | 0.002153*** | 0.001796*** | |
| (0.000) | (0.000) | (0.000) | ||
| X + dry anomalies × no. upstream dams | −0.023459+ | −0.04423*** | −0.018970** | |
| (0.014) | (0.007) | (0.006) | ||
| N | 63,154 | 703,512 | 703,512 | 703,512 |
| Kleibergen–Papp LM-stat | 107.6 | 123.471 | 180.597 | 141.091 |
| Kleibergen–Papp LM P value | 0.000 | 0.0000 | 0.0000 | 0.0000 |
| Kleibergen–Papp F-stat | 25.32 | 30.491 | 44.888 | 35.107 |
Dependent variable in column 2 is the change in log NPP in a grid cell. Dependent variable in columns 3 to 5 is the 5-y average annual change in log cropland area in a grid cell. All regression models include controls for year and country fixed effects as well as temperature, population, country–year trends, terrain roughness, aquifer presence, and CTI. Columns 3 to 5 also control for annual precipitation. X + wet (dry) rainfall anomalies is a time-varying dummy variable indicating if rainfall was at least 1 SD higher (lower) than the long-run mean of the grid cell for X or more years out of the prior 10 y, where X is given in the second row. Upstream dams is a count variable which indicates the number of upstream dams from the grid cell. Statistical significance is given by +P < 0.10, *P < 0.05, **P < 0.01, and ***P < 0.001. Robust clustered SEs are in parentheses. The regressions pass diagnostic tests for instrument relevance (Kleibergen–Papp LM test) and the test for weak instruments (Kleibergen–Papp Wald test) providing supporting evidence about the validity of the instrumental variables. Additional details are provided in Materials and Methods and SI Appendix.