## 3 Results
### Reductions in Runoff  
The monitoring equipment was installed in March 2018, and data collection was planned for a 12-month period. However, there were challenges initially with the remote transfer of data, due to extremely low signal. The data collection period spans 22 March 2018-25 February 2019. Flow level was recorded at 5 min intervals. Therefore, there was the potential for 98,208 data points to be collected from each manhole during this period. There were 33,547 points recorded in manhole 1 (34.2% data completeness); 29,028 recorded in manhole 6 (29.6% data completeness); and 31,773 recorded in manhole 7 (32.4% data completeness). A rain gauge, which was installed later in the project on the community centre roof, recorded fifteen heavy rainfall events (defined by a rainfall intensity of 12-18 mm/h) between November-December 2018. However, data for the manhole level flow in this  
Figure 7: Total monthly rainfall (mm) in Durham in 2018 compared to average Met Office UK climate-historic station data (1880–2018) (primary \(x\)-axis) [40], and weekly total rainfall (mm) from Stanley East Kyo Farm rain gauge (secondary \(x\)-axis) [41]. The Stanley rain gauge is the nearest Environment Agency telemetered rain gauge to South Moor, where the data are reported from a tipping bucket rain gauge as accumulated totals for each 15 min period and summed per time interval [41]. period was not captured, perhaps due to signal strength or power issues. This period of the data collection has been omitted from the analysis below. There were two periods where data was collected consistently, with minimal gaps, in both manhole 6 and 7: 20 August-22 October 2018; and 18 January-25 February 2019 (Figure 8). Rainfall fell within the mean historic average for these periods. During the first period there was the potential for 18,432 individual data points to be recorded for each manhole and during the second period, there was the potential for 11,232 data points. Analysis of the raw data set showed 18,155 data points (98.5% completeness) for manhole 6, and 18,284 data points (99.2% completeness) for manhole 7 over the first, 64-day period (Table 1). There were 10,856 data points (96.7% completeness) recorded for manhole 6, and 7996 data points (71.2% completeness) for manhole 7 over the second, 39-day period. Figure 8: Level measurement in millimetres in manhole 6 (blue line) and manhole 7 (grey line) between 20 August–22 October 2018 (**A**) and 18 January–25 February 2019 (**B**). Daily rainfall is provided on a secondary axis in both. There were significant gaps in data collection between 23 October 2018–17 January 2019. Flow levels were averaged per day. A paired-samples t-test was run to evaluate if there was a mean difference in manhole level before and after the SuDS interventions on Poplar St (i.e., manhole 6 = \"before\" and manhole 7 = \"after\"). The level in manhole 6 was higher (\(163.9\pm 15.5\) mm) than the level in manhole 7 (\(124\pm 3.8\) mm) (Figure 8A). There was a statistically significant decrease in flow level in the manhole downstream of the SuDS trees compared to the flow level upstream, t(\(63\)) = \(18.125\), \(p<0.0005\) (Table 1). The assumption of normality of data was violated, as assessed by [PERSON]'s test (\(p\) = 0.001) (Figure 9A,B). Whilst the paired samples t-test is robust to violations of normality, a non-parametric alternative, the Wilcoxon signed-rank test, was carried out. The distribution of differences (Figure 10A) was not symmetrical violating one of the assumptions of the test. A related-samples sign test revealed that, during first period (64 days, 20 August-22 October 2018), the median flow level in the manhole downstream of the SuDS trees was statistically significantly lower (\(123.3\) mm) than the median flow level in the manhole upstream of these interventions (\(159.5\) mm), \(z=-7.875\), \(p<0.0005\) (Table 1).