Figure 1.
Map of the study region (1-1: Greater and Lesser Khingan Mountain Region; 1-2: Changbai Mountain-Wandalshan Mountainous Hilly Region; 1-3: Northeast Rolling Hilly Region; 1-4: Sandstorm Region of the Songliao Plain; 1-5: Mountainous Hilly Region southeast of the Greater Mountains Region; 1-6: Hulunbuir Hilly Plain Region).
Figure 1.
Map of the study region (1-1: Greater and Lesser Khingan Mountain Region; 1-2: Changbai Mountain-Wandalshan Mountainous Hilly Region; 1-3: Northeast Rolling Hilly Region; 1-4: Sandstorm Region of the Songliao Plain; 1-5: Mountainous Hilly Region southeast of the Greater Mountains Region; 1-6: Hulunbuir Hilly Plain Region).
Figure 2.
Average monthly precipitation from 1981 to 2015.
Figure 2.
Average monthly precipitation from 1981 to 2015.
Figure 3.
Rainfall erosion indices in the Rolling Hilly Region of Northeast China from 1981 to 2015, (a) NREI and (b) EREI. NREI, normal rainfall erosivity indices; ARE, annual rainfall erosivity; WRE, wet season rainfall erosivity; DRE, dry season rainfall erosivity; TWRE, typical wet month rainfall erosivity; TDRE, typical dry-month rainfall erosivity; EREI, extreme rainfall erosivity indices; RE × 1 day, rainfall erosivity maximum one-day rainfall erosivity in a year; RE × 5 day, maximum five-day rainfall erosivity in a year; RE50, the sum of storm (precipitation ≥ 50 mm) rainfall erosivity in a year; CRE, maximum continuous rainfall erosivity in a year, unit: .
Figure 3.
Rainfall erosion indices in the Rolling Hilly Region of Northeast China from 1981 to 2015, (a) NREI and (b) EREI. NREI, normal rainfall erosivity indices; ARE, annual rainfall erosivity; WRE, wet season rainfall erosivity; DRE, dry season rainfall erosivity; TWRE, typical wet month rainfall erosivity; TDRE, typical dry-month rainfall erosivity; EREI, extreme rainfall erosivity indices; RE × 1 day, rainfall erosivity maximum one-day rainfall erosivity in a year; RE × 5 day, maximum five-day rainfall erosivity in a year; RE50, the sum of storm (precipitation ≥ 50 mm) rainfall erosivity in a year; CRE, maximum continuous rainfall erosivity in a year, unit: .
Figure 4.
Mann–Kendall test statistics of (a) NREI and (b) EREI. NREI, normal rainfall erosivity indices; ARE, annual rainfall erosivity; WRE, wet season rainfall erosivity; DRE, dry season rainfall erosivity; TWRE, typical wet month rainfall erosivity; TDRE, typical dry-month rainfall erosivity; EREI, extreme rainfall erosivity indices; RE × 1 day, rainfall erosivity maximum one-day rainfall erosivity in a year; RE × 5 day, maximum five-day rainfall erosivity in a year; RE50, the sum of storm (precipitation ≥ 50 mm) rainfall erosivity in a year; CRE, maximum continuous rainfall erosivity in a year.
Figure 4.
Mann–Kendall test statistics of (a) NREI and (b) EREI. NREI, normal rainfall erosivity indices; ARE, annual rainfall erosivity; WRE, wet season rainfall erosivity; DRE, dry season rainfall erosivity; TWRE, typical wet month rainfall erosivity; TDRE, typical dry-month rainfall erosivity; EREI, extreme rainfall erosivity indices; RE × 1 day, rainfall erosivity maximum one-day rainfall erosivity in a year; RE × 5 day, maximum five-day rainfall erosivity in a year; RE50, the sum of storm (precipitation ≥ 50 mm) rainfall erosivity in a year; CRE, maximum continuous rainfall erosivity in a year.
Figure 5.
Sliding t-test statistics of (a) NREI and (b) EREI. NREI, normal rainfall erosivity indices; ARE, annual rainfall erosivity; WRE, wet season rainfall erosivity; DRE, dry season rainfall erosivity; TWRE, typical wet month rainfall erosivity; TDRE, typical dry-month rainfall erosivity; EREI, extreme rainfall erosivity indices; RE × 1 day, rainfall erosivity maximum one-day rainfall erosivity in a year; RE × 5 day, maximum five-day rainfall erosivity in a year; RE50, the sum of storm (precipitation ≥ 50 mm) rainfall erosivity in a year; CRE, maximum continuous rainfall erosivity in a year.
Figure 5.
Sliding t-test statistics of (a) NREI and (b) EREI. NREI, normal rainfall erosivity indices; ARE, annual rainfall erosivity; WRE, wet season rainfall erosivity; DRE, dry season rainfall erosivity; TWRE, typical wet month rainfall erosivity; TDRE, typical dry-month rainfall erosivity; EREI, extreme rainfall erosivity indices; RE × 1 day, rainfall erosivity maximum one-day rainfall erosivity in a year; RE × 5 day, maximum five-day rainfall erosivity in a year; RE50, the sum of storm (precipitation ≥ 50 mm) rainfall erosivity in a year; CRE, maximum continuous rainfall erosivity in a year.
Figure 6.
Spatial distribution of NREI. NREI, normal rainfall erosivity indices; ARE, annual rainfall erosivity; WRE, wet season rainfall erosivity; DRE, dry season rainfall erosivity; TWRE, typical wet month rainfall erosivity; TDRE, typical dry-month rainfall erosivity.
Figure 6.
Spatial distribution of NREI. NREI, normal rainfall erosivity indices; ARE, annual rainfall erosivity; WRE, wet season rainfall erosivity; DRE, dry season rainfall erosivity; TWRE, typical wet month rainfall erosivity; TDRE, typical dry-month rainfall erosivity.
Figure 7.
Spatial distribution of EREI. EREI, extreme rainfall erosivity indices, RE × 1 day, rainfall erosivity maximum one-day rainfall erosivity in a year; RE × 5 day, maximum five-day rainfall erosivity in a year; RE50, the sum of storm (precipitation ≥ 50 mm) rainfall erosivity in a year; CRE, maximum continuous rainfall erosivity in a year.
Figure 7.
Spatial distribution of EREI. EREI, extreme rainfall erosivity indices, RE × 1 day, rainfall erosivity maximum one-day rainfall erosivity in a year; RE × 5 day, maximum five-day rainfall erosivity in a year; RE50, the sum of storm (precipitation ≥ 50 mm) rainfall erosivity in a year; CRE, maximum continuous rainfall erosivity in a year.
Figure 8.
Trend in REI. REI, rainfall erosivity indices; ARE, annual rainfall erosivity; WRE, wet season rainfall erosivity; DRE, dry season rainfall erosivity; TWRE, typical wet month rainfall erosivity; TDRE, typical dry-month rainfall erosivity; RE × 1 day, rainfall erosivity maximum one-day rainfall erosivity in a year; RE × 5 day, maximum five-day rainfall erosivity in a year; RE50, the sum of storm (precipitation ≥ 50 mm) rainfall erosivity in a year; CRE, maximum continuous rainfall erosivity in a year.
Figure 8.
Trend in REI. REI, rainfall erosivity indices; ARE, annual rainfall erosivity; WRE, wet season rainfall erosivity; DRE, dry season rainfall erosivity; TWRE, typical wet month rainfall erosivity; TDRE, typical dry-month rainfall erosivity; RE × 1 day, rainfall erosivity maximum one-day rainfall erosivity in a year; RE × 5 day, maximum five-day rainfall erosivity in a year; RE50, the sum of storm (precipitation ≥ 50 mm) rainfall erosivity in a year; CRE, maximum continuous rainfall erosivity in a year.
Table 1.
Classification of daily rainfall.
Table 1.
Classification of daily rainfall.
Level | Daily Rainfall Amount |
---|
Drizzle | <0.1 |
Light rain | 0.1~9.9 |
Moderate rain | 10.0~24.9 |
Heavy rain | 25.0~49.9 |
Torrential rain | 50.0~99.9 |
Downpour | 100.0~249.9 |
Heavy downpour | ≥250.0 |
Table 2.
Definition of normal and extreme rainfall indices.
Table 2.
Definition of normal and extreme rainfall indices.
Category | Index | Definition |
---|
Normal | ARE | Annual rainfall erosivity |
WRE | Wet season rainfall erosivity |
DRE | Dry season rainfall erosivity |
TWRE | Typical wet month rainfall erosivity |
TDRE | Typical dry-month rainfall erosivity |
Extreme | RE × 1 day | Maximum one-day rainfall erosivity in a year |
RE × 5 day | Maximum five-day rainfall erosivity in a year |
RE50 | The sum of storm (precipitation ≥ 50 mm) rainfall erosivity in a year |
CRE | Maximum continuous rainfall erosivity in a year |
Table 3.
Classification of the Hurst exponent.
Table 3.
Classification of the Hurst exponent.
Classification | H Range | Classification | H Range |
---|
Ⅰ | 0.50 < H ≤ 0.55 | −Ⅰ | 0.45 < H ≤ 0.50 |
Ⅱ | 0.55 < H ≤ 0.65 | −Ⅱ | 0.35 < H ≤ 0.45 |
Ⅲ | 0.65 < H ≤ 0.75 | −Ⅲ | 0.25 < H ≤ 0.35 |
Ⅳ | 0.75 < H ≤ 0.80 | −Ⅳ | 0.20 < H ≤ 0.25 |
Ⅴ | 0.80 < H ≤ 1.00 | −Ⅴ | 0.00 < H ≤ 0.20 |
Table 4.
Correlations between NREI. NREI, normal rainfall erosivity indices; ARE, annual rainfall erosivity; WRE, wet season rainfall erosivity; DRE, dry season rainfall erosivity; TWRE, typical wet month rainfall erosivity; TDRE, typical dry-month rainfall erosivity.
Table 4.
Correlations between NREI. NREI, normal rainfall erosivity indices; ARE, annual rainfall erosivity; WRE, wet season rainfall erosivity; DRE, dry season rainfall erosivity; TWRE, typical wet month rainfall erosivity; TDRE, typical dry-month rainfall erosivity.
| ARE | WRE | DRE | TWRE | TDRE |
---|
ARE | 1 * | 0.9 * | 0.8 * | 0.9 * | 0.6 * |
WRE | 0.9 * | 1 * | 0.8 * | 0.8 * | 0.4 * |
DRE | 0.8 * | 0.8 * | 1 * | 0.7 * | 0.6 * |
TWRE | 0.9 * | 0.8 * | 0.7 * | 1 * | 0.6 * |
TDRE | 0.6 * | 0.4 * | 0.6 * | 0.6 * | 1 * |
Table 5.
Trends and values of NREI in Heilongjiang, Jilin, and Liaoning. , the coefficient of variation; NREI, normal rainfall erosivity indices; ARE, annual rainfall erosivity; WRE, wet season rainfall erosivity; DRE, dry season rainfall erosivity; TWRE, typical wet month rainfall erosivity; TDRE, typical dry-month rainfall erosivity.
Table 5.
Trends and values of NREI in Heilongjiang, Jilin, and Liaoning. , the coefficient of variation; NREI, normal rainfall erosivity indices; ARE, annual rainfall erosivity; WRE, wet season rainfall erosivity; DRE, dry season rainfall erosivity; TWRE, typical wet month rainfall erosivity; TDRE, typical dry-month rainfall erosivity.
Index | Heilongjiang | Jilin | Liaoning |
---|
Trend | | Trend | | Trend | |
---|
ARE | −43.9 | 0.3 | −71.9 | 0.3 | 14.3 | 0.4 |
WRE | −38.5 | 0.3 | −82.6 | 0.3 | −32.5 | 0.5 |
DRE | −5.4 | 0.8 | 10.7 | 0.8 | 46.8 | 0.9 |
TWRE | −15.2 | 0.4 | −78.8 | 0.5 | 44.5 | 0.8 |
TDRE | 0.0 | 0.0 | 0.0 | 4.4 | 0.0 | 4.7 |
Table 6.
Correlations between EREI. EREI, extreme rainfall erosivity indices; RE × 1 day, rainfall erosivity maximum one-day rainfall erosivity in a year; RE × 5 day, maximum five-day rainfall erosivity in a year; RE50, the sum of storm (precipitation ≥ 50 mm) rainfall erosivity in a year; CRE, maximum continuous rainfall erosivity in a year.
Table 6.
Correlations between EREI. EREI, extreme rainfall erosivity indices; RE × 1 day, rainfall erosivity maximum one-day rainfall erosivity in a year; RE × 5 day, maximum five-day rainfall erosivity in a year; RE50, the sum of storm (precipitation ≥ 50 mm) rainfall erosivity in a year; CRE, maximum continuous rainfall erosivity in a year.
| RE × 1 day | RE × 5 day | RE50 | CRE |
---|
RE × 1 day | 1 * | 0.97 * | 0.9 * | 0.98 * |
RE × 5 day | 0.97 * | 1 * | 0.98 * | 0.99 * |
RE50 | 0.95 * | 0.98 * | 1 * | 0.97 * |
CRE | 0.98 * | 0.99 * | 0.97 * | 1 * |
Table 7.
Trends and values of EREI in Heilongjiang, Jilin, and Liaoning. , the coefficient of variation; EREI, extreme rainfall erosivity indices, RE × 1 day, rainfall erosivity maximum one-day rainfall erosivity in a year; RE × 5 day, maximum five-day rainfall erosivity in a year; RE50, the sum of storm (precipitation ≥ 50 mm) rainfall erosivity in a year; CRE, maximum continuous rainfall erosivity in a year.
Table 7.
Trends and values of EREI in Heilongjiang, Jilin, and Liaoning. , the coefficient of variation; EREI, extreme rainfall erosivity indices, RE × 1 day, rainfall erosivity maximum one-day rainfall erosivity in a year; RE × 5 day, maximum five-day rainfall erosivity in a year; RE50, the sum of storm (precipitation ≥ 50 mm) rainfall erosivity in a year; CRE, maximum continuous rainfall erosivity in a year.
Index | Heilongjiang | Jilin | Liaoning |
---|
Trend | | Trend | | Trend | |
---|
RE × 1 day | −8.1 | 0.3 | −16.6 | 0.4 | 31.0 | 0.6 |
RE × 5 day | −17.3 | 0.3 | −28.7 | 0.3 | 31.0 | 0.6 |
RE50 | −11.0 | 0.5 | −30.2 | 0.7 | 56.9 | 0.9 |
CRE | −8.9 | 0.3 | −23.2 | 0.4 | 53.3 | 0.7 |
Table 8.
The Hurst exponent of REI. REI, rainfall erosivity indices; NREI, normal rainfall erosivity indices; ARE, annual rainfall erosivity; WRE, wet season rainfall erosivity; DRE, dry season rainfall erosivity; TWRE, typical wet month rainfall erosivity; TDRE, typical dry-month rainfall erosivity; EREI, extreme rainfall erosivity indices, RE × 1 day, rainfall erosivity maximum one-day rainfall erosivity in a year; RE × 5 day, maximum five-day rainfall erosivity in a year; RE50, the sum of storm (precipitation ≥ 50 mm) rainfall erosivity in a year; CRE, maximum continuous rainfall erosivity in a year.
Table 8.
The Hurst exponent of REI. REI, rainfall erosivity indices; NREI, normal rainfall erosivity indices; ARE, annual rainfall erosivity; WRE, wet season rainfall erosivity; DRE, dry season rainfall erosivity; TWRE, typical wet month rainfall erosivity; TDRE, typical dry-month rainfall erosivity; EREI, extreme rainfall erosivity indices, RE × 1 day, rainfall erosivity maximum one-day rainfall erosivity in a year; RE × 5 day, maximum five-day rainfall erosivity in a year; RE50, the sum of storm (precipitation ≥ 50 mm) rainfall erosivity in a year; CRE, maximum continuous rainfall erosivity in a year.
Category | Index | Hurst Exponent | Classification |
---|
NREI | ARE | 0.33 | −Ⅱ |
WRE | 0.33 | −Ⅱ |
DRE | 0.44 | −Ⅲ |
TWRE | 0.41 | −Ⅲ |
TDRE | | |
EREI | RE × 1 day | 0.38 | −Ⅲ |
RE × 5 day | 0.39 | −Ⅲ |
RE50 | 0.39 | −Ⅲ |
CRE | 0.38 | −Ⅲ |
Table 9.
The Hurst exponent of REI in Heilongjiang, Jilin, and Liaoning. REI, rainfall erosivity indices; NREI, normal rainfall erosivity indices; ARE, annual rainfall erosivity; WRE, wet season rainfall erosivity; DRE, dry season rainfall erosivity; TWRE, typical wet month rainfall erosivity; TDRE, typical dry-month rainfall erosivity; EREI, extreme rainfall erosivity indices, RE × 1 day, rainfall erosivity maximum one-day rainfall erosivity in a year; RE × 5 day, maximum five-day rainfall erosivity in a year; RE50, the sum of storm (precipitation ≥ 50 mm) rainfall erosivity in a year; CRE, maximum continuous rainfall erosivity in a year.
Table 9.
The Hurst exponent of REI in Heilongjiang, Jilin, and Liaoning. REI, rainfall erosivity indices; NREI, normal rainfall erosivity indices; ARE, annual rainfall erosivity; WRE, wet season rainfall erosivity; DRE, dry season rainfall erosivity; TWRE, typical wet month rainfall erosivity; TDRE, typical dry-month rainfall erosivity; EREI, extreme rainfall erosivity indices, RE × 1 day, rainfall erosivity maximum one-day rainfall erosivity in a year; RE × 5 day, maximum five-day rainfall erosivity in a year; RE50, the sum of storm (precipitation ≥ 50 mm) rainfall erosivity in a year; CRE, maximum continuous rainfall erosivity in a year.
Category | Index | Heilongjiang | Jilin | Liaoning |
---|
NREI | ARE | 0.30 | 0.33 | 0.31 |
WRE | 0.30 | 0.32 | 0.32 |
DRE | 0.42 | 0.40 | 0.44 |
TWRE | 0.39 | 0.34 | 0.40 |
TDRE | | | |
EREI | RE × 1 day | 0.35 | 0.32 | 0.32 |
RE × 5 day | 0.33 | 0.34 | 0.35 |
RE50 | 0.35 | 0.34 | 0.30 |
CRE | 0.29 | 0.31 | 0.35 |
Table 10.
Correlations between REI and geographic factors. ARE, annual rainfall erosivity; WRE, wet season rainfall erosivity; DRE, dry season rainfall erosivity; TWRE, typical wet month rainfall erosivity; TDRE, typical dry-month rainfall erosivity; RE × 1 day, rainfall erosivity maximum one-day rainfall erosivity in a year; RE × 5 day, maximum five-day rainfall erosivity in a year; RE50, the sum of storm (precipitation ≥ 50 mm) rainfall erosivity in a year; CRE, maximum continuous rainfall erosivity in a year.
Table 10.
Correlations between REI and geographic factors. ARE, annual rainfall erosivity; WRE, wet season rainfall erosivity; DRE, dry season rainfall erosivity; TWRE, typical wet month rainfall erosivity; TDRE, typical dry-month rainfall erosivity; RE × 1 day, rainfall erosivity maximum one-day rainfall erosivity in a year; RE × 5 day, maximum five-day rainfall erosivity in a year; RE50, the sum of storm (precipitation ≥ 50 mm) rainfall erosivity in a year; CRE, maximum continuous rainfall erosivity in a year.
| ARE | WRE | DRE | TWRE | TDRE | RE × 1 Day | RE × 5 Day | RE50 | CRE |
---|
Lat | −0.7 * | −0.7 * | −0.7 * | −0.5 * | −0.4 * | −0.7 * | −0.7 * | −0.7 * | −0.7 * |
Lon | −0.2 | −0.4 * | −0.4 * | −0.2 | −0.2 | −0.4 * | −0.4 * | −0.3 * | −0.4 * |
Alt | −0.1 | −0.3 * | −0.3 * | 0 | 0.1 | −0.3 * | −0.3 * | −0.3 * | −0.3 * |
Table 11.
Percentage of sites with upward and downward trends in each rainfall erosivity index. NREI, normal rainfall erosivity indices; ARE, annual rainfall erosivity; WRE, wet season rainfall erosivity; DRE, dry season rainfall erosivity; TWRE, typical wet month rainfall erosivity; TDRE, typical dry-month rainfall erosivity; EREI, extreme rainfall erosivity indices, RE × 1 day, rainfall erosivity maximum one-day rainfall erosivity in a year; RE × 5 day, maximum five-day rainfall erosivity in a year; RE50, the sum of storm (precipitation ≥ 50 mm) rainfall erosivity in a year; CRE, maximum continuous rainfall erosivity in a year.
Table 11.
Percentage of sites with upward and downward trends in each rainfall erosivity index. NREI, normal rainfall erosivity indices; ARE, annual rainfall erosivity; WRE, wet season rainfall erosivity; DRE, dry season rainfall erosivity; TWRE, typical wet month rainfall erosivity; TDRE, typical dry-month rainfall erosivity; EREI, extreme rainfall erosivity indices, RE × 1 day, rainfall erosivity maximum one-day rainfall erosivity in a year; RE × 5 day, maximum five-day rainfall erosivity in a year; RE50, the sum of storm (precipitation ≥ 50 mm) rainfall erosivity in a year; CRE, maximum continuous rainfall erosivity in a year.
Category | Index | RHRNEC | Heilongjiang | Jilin | Liaoning |
---|
Increase | Decrease | Increase | Decrease | Increase | Decrease | Increase | Decrease |
---|
NREI | ARE | 40.5 | 59.5 | 47.7 | 52.3 | 26.1 | 73.9 | 50.0 | 50.0 |
WRE | 39.2 | 60.8 | 50.0 | 50.0 | 26.1 | 73.9 | 25.0 | 75.0 |
DRE | 51.9 | 48.1 | 31.8 | 68.2 | 69.6 | 30.4 | 100.0 | 0.0 |
TWRE | 43.0 | 57.0 | 50.0 | 50.0 | 17.4 | 82.6 | 87.5 | 12.5 |
TDRE | 5.1 | 7.6 | 0.0 | 0.0 | 8.7 | 13.0 | 12.5 | 12.5 |
EREI | RE × 1 day | 46.8 | 53.2 | 45.5 | 54.5 | 43.5 | 56.5 | 62.5 | 37.5 |
RE × 5 day | 45.6 | 54.4 | 50.0 | 50.0 | 34.8 | 65.2 | 75.0 | 25.0 |
RE50 | 46.8 | 53.2 | 52.3 | 47.7 | 39.1 | 60.9 | 62.5 | 37.5 |
CRE | 48.1 | 51.9 | 50.0 | 50.0 | 39.1 | 60.9 | 87.5 | 12.5 |